The document provides code snippets to copy the contents of one array into another array in reverse order using different approaches like loops, pointers, and functions. It also includes code to reverse an array without using additional memory by swapping elements, and to reverse an array using pointers.

1. Write a program to copy the contents of one array into
another in the reverse order.
Source Code :
#include<stdio.h>
void main()
{
int a[10],b[10],i,j;
clrscr();
printf("nEnter Elements : ");
for(i=0;i<10;i++)
{
scanf("%d",&a[i]);
}
for(i=0,j=9;i<10;i++,j--)
{
b[i]=a[j];
}
printf("nArray after Copying in Reverse Order : ");
for(i=0;i<10;i++)
{
printf("%d ",b[i]);
}
getch();
}
Output :
Enter Elements : 2 6 3 5 9 8 7 4 1 0
Array after Copying in Reverse Order : 0 1 4 7 8 9 5 3 6 2
#include<stdio.h>
#include<conio.h>
void main()
{
int i,n=10,a[20],b[20];
clrscr();
printf("How many element do you wish to enter in array? :"); scanf("%d",&n);
printf("nEnter the Elements:n");
for(i=0;i<n;i++)
{
printf("Enter Element No %d : ",1+i);
scanf("%d",&a[i]);

2. }
printf("n Original ARRAY: n");
for(i=0;i<n;i++)
printf(" %d ",a[i]);
for(i=0;i<n;i++)
{
b[n-1-i]=a[i];
}
printf("n Copied ARRAY: n");
for(i=0;i<n;i++)
printf(" %d ",b[i]);
getch();
}
//***********************
//www.botskool.com
//***********************
Program to print array element in reverse order.
Code for Program to print array element in reverse order in C Programming
#include<conio.h>
#include<stdio.h>
#include<stdlib.h>
int main()
{
int *ptr,i,n;
clrscr();
printf("Enter the no of elements:");
scanf("%d",&n);
ptr=(int *)malloc(sizeof(int)*n);
if(ptr==NULL)
{
printf("Not enough memory");
exit(1);
}
for(i=0; i<n; i++)
{
printf("Enter %d element : ",i+1);
scanf("%d",&ptr[i]);
}
printf("Array in original ordern");

3. for(i=0; i<n; i++)
{
printf("%dn",ptr[i]);
}
printf("Array in reverse ordern");
for(i=n-1; i>=0; i--)
{
printf("%dn",ptr[i]);
}
getch();
return 0;
}
void reverse( int array[], int length)
{
int ii, temp;
int jj = 0;
int *tempArray = (int)malloc( length * sizeof( int));
for ( ii = length-1; ii >= 0; ii--)
{
tempArray[jj] = array[ii];
jj += 1;
}
array = *tempArray;
for (ii = 0; ii <= length-1; ii++)
{
printf("DEBUGn");
temp = tempArray[ii];
array[ii] = temp;
}
free( tempArray);
}
#include<stdio.h>
#include<conio.h>
voidmain()
{
int i,j,a[100],b[100];
printf("How many numbers youwant to store:=n");
scanf("%d",&j);
printf("Enter the numbers:=n");
for(i=0;i<j;i++)
{
scanf("%d",&a[i]);
}
for(i=0;i<j;i++)
{
b[i]=a[j-i-1];

4. }
printf("Reversedorder:=n");
for(i=0;i<j;i++)
{
printf("%dn",b[i]);
}
getch();
}
Write a program to copy the contents of one array into another in the reverse
order.
void main()
{
int arr1[5]={1,2,3,4,5};
int arr2[5];
int i,k;
for (i=4,k=0;i>=0;i--,k++)
arr2[k]=arr1[i];
for(i=0;i<5;i++)
printf("nValue of arr2[%d] is %d",i,arr2[i]);
}
With Pointers
void main()
{
int arr1[5]={1,2,3,4,5};
int arr2[5];
int *m;
int i,*j,k,l=5;
j=arr1;
m=arr2;
func(j,m,l);
for(i=0;i<5;i++)
printf("nValue of arr2[%d] is %d",i,arr2[i]);
}
func(int *j, int *m, int l)
{
int i;
for(j=j+4,i=0;i<5;i++,j--,m++)
*m=*j;
}
#include<stdio.h>

5. #include<conio.h>
main()
{
int num[10];
int x;
for(x=0;x<10;x++)
{
printf("Enter number %d : ",x);
scanf("%d", &num[x]);
}
for(x=0;x<10;x++)
{
printf(" %d ",num[x]);
}
//clrscr ();
num[x]=0;
for(x=10;x>-1;x--)
{
printf(" %d ",num[x]);
}
getch();
}
C program to reverse an array: This program reverses the array elements. For example if a is
an array of integers with three elements such that
a[0] = 1
a[1] = 2
a[2] = 3
Then on reversing the array will be
a[0] = 3
a[1] = 2
a[0] = 1
Given below is the c code to reverse an array.
C programming code
#include <stdio.h>
int main()
{
int n, c, d, a[100], b[100];

6. printf("Enter the number of elements in arrayn");
scanf("%d", &n);
printf("Enter the array elementsn");
for (c = 0; c < n ; c++)
scanf("%d", &a[c]);
/*
* Copying elements into array b starting from end of array a
*/
for (c = n - 1, d = 0; c >= 0; c--, d++)
b[d] = a[c];
/*
* Copying reversed array into original.
* Here we are modifying original array, this is optional.
*/
for (c = 0; c < n; c++)
a[c] = b[c];
printf("Reverse array isn");
for (c = 0; c < n; c++)
printf("%dn", a[c]);
return 0;
}
Download Reverse array program.
Output of program:

7. Reverse array by swapping (without using additionalmemory)
#include <stdio.h>
int main() {
int array[100], n, c, t, end;
scanf("%d", &n);
end = n - 1;
for (c = 0; c < n; c++) {
scanf("%d", &array[c]);
}
for (c = 0; c < n/2; c++) {
t = array[c];
array[c] = array[end];
array[end] = t;
end--;
}
printf("Reversed array elements are:n");
for (c = 0; c < n; c++) {
printf("%dn", array[c]);
}
return 0;
}
C program to reverse an array using pointers
#include <stdio.h>
#include <stdlib.h>
void reverse_array(int*, int);
int main()
{
int n, c, *pointer;
scanf("%d",&n);
pointer = (int*)malloc(sizeof(int)*n);
if( pointer == NULL )
exit(EXIT_FAILURE);
for ( c = 0 ; c < n ; c++ )
scanf("%d",(pointer+c));
reverse_array(pointer, n);
printf("Original array on reversal isn");
for ( c = 0 ; c < n ; c++ )

8. printf("%dn",*(pointer+c));
free(pointer);
return 0;
}
void reverse_array(int *pointer, int n)
{
int *s, c, d;
s = (int*)malloc(sizeof(int)*n);
if( s == NULL )
exit(EXIT_FAILURE);
for ( c = n - 1, d = 0 ; c >= 0 ; c--, d++ )
*(s+d) = *(pointer+c);
for ( c = 0 ; c < n ; c++ )
*(pointer+c) = *(s+c);
free(s);
}

9. Chap 8[D]a Search quantity of instances in Array
Twenty-five numbers are entered from the keyboard into an array. The number to
be searched is entered through the keyboard by the user. Write a program to find
if the number to be searched is present in the array and if it is present, display the
number of times it appears in the array.
void main()
{
int arr[25];
int a,d,i;
for(i=0;i<25;i++)
{
printf("nKey %d) value",i);
scanf("%d",&arr[i]);
}
printf("n25 numbers stored, enter any integer again");
scanf("%d",&d);
for(i=0,a=0;i<25;i++)
{
if(arr[i]==d)
a++;
}
if(a>0)
printf("nThe integer appeared %d times in the array",a);
else
printf("nThe integer did not appear in the array");
}
hap8[D]b Finding +tive -tive zeros, odd and even numbers in array
Twenty-five numbers are entered from the keyboard into an array. Write a
program to find out how many of them are positive, how many are negative, how
many are even and how many odd.
void main()
{
int arr[25];
int a,b,c,d,e,i;
a=0;
b=0;

10. c=0;
d=0;
e=0;
for(i=0;i<25;i++)
{
printf("nKey the %d) value",i);
scanf("%d",&arr[i]);
}
for(i=0;i<25;i++)
{
if(arr[i]>0)
a++;
if(arr[i]<0)
b++;
if(arr[i]==0)
c++;
if(arr[i]%2==0)
d++;
else
e++;
}
if(a>0)
printf("nThere are %d positive integers",a);
if(b>0)
printf("nThere are %d negative integers",b);
if(c>0)
printf("nThere are %d zeros",c);
if(d>0)
printf("nThere are %d even numbers",d);
if(e>0)
printf("nThere are %d odd numbers",e);
}
Chap8[D]c Selection sort

11. Implement the Selection Sort, Bubble Sort and Insertion sort algorithms on a set
of 25 numbers. (Refer Figure 8.11 for the logic of the algorithms) − Selection sort
− Bubble Sort − Insertion Sort
/* Selection sort */
void main()
{
int arr[25];
int a,b,d,i;
printf("nInput 25 numbers into array");

12. for(i=0;i<25;i++)
{
printf("nKey the %d) value",i);
scanf("%d",&arr[i]);
}
printf("nStarting selection sorting");
for(i=0;i<24;i++)
{
for(d=i+1;d<25;d++)
{
a=arr[i];
b=arr[d];
arr[i]=b;
arr[d]=a;
}
}
printf("nSelection sorting done");
for(i=0;i<25;i++)
printf("n%d) value is %d",i,arr[i]);
}
Chap8[D]c Buuuubbbble sort
Implement the Selection Sort, Bubble Sort and Insertion sort algorithms on a set
of 25 numbers. (Refer Figure 8.11 for the logic of the algorithms)− Selection sort
− Bubble Sort − Insertion Sort

13. /*Bubble sort*/
void main()
{
int arr[25];
int a,b,c,d,i;
printf("nInput 25 numbers into the array");
for(i=0;i<25;i++)
{
printf("nKey the %d) value",i);
scanf("%d",&arr[i]);
}

14. printf("nStarting bubble sort");
for(i=24;i>0;i--)
{
for(b=0,c=b+1;c <=i;b++,c ++)
{
a=arr[b];
d=arr[c];
arr[b]=d;
arr[c]=a;
}
}
printf("nBubble sort done");
for(i=0;i<25;i++)
printf("n%d value is %d",i,arr[i]);
}
Chap8[D]c Insertion sort
Implement the Selection Sort, Bubble Sort and Insertion sort algorithms on a set
of 25 numbers. (Refer Figure 8.11 for the logic of the algorithms) − Selection sort
− Bubble Sort − Insertion Sort
/*Insertion sort*/
void main()

15. {
int arr[25];
int a,b,c,i;
printf("nInput 25 numbers into the array");
for(i=0;i<25;i++)
{
printf("nKey in the %d) value",i);
scanf("%d",&arr[i]);
}
printf("nStarting insertion sort");
for(a=1;a<25;a++)
{
b=arr[0];
c=arr[a];
arr[0]=c;
arr[a]=b;
}
printf("nInsertion sort done");
for(i=0;i<25;i++)
printf("nThe %d) value is%d",i,arr[i]);
}
Chap8[D]d Sieve of Eratosthenes
Implement the following procedure to generate prime numbers from 1 to 100 into
a program. This procedure is called sieve of Eratosthenes.
step 1 Fill an array num[100] with numbers from 1 to 100
step 2 Starting with the second entry in the array, set all its multiples to zero.
step 3 Proceed to the next non-zero element and set all its multiples to zero.
step 4 Repeat step 3 till you have set up the multiples of all the non-zero elements
to zero
step 5 At the conclusion of step 4, all the non-zero entries left in the array would
be prime numbers, so print out these numbers.

16. Chap8[I]a Reversing contents and copy to another array
Write a program to copy the contents of one array into another in the reverse
order.
void main()
{
int arr1[5]={1,2,3,4,5};
int arr2[5];
int i,k;
for (i=4,k=0;i>=0;i--,k++)
arr2[k]=arr1[i];
for(i=0;i<5;i++)
printf("nValue of arr2[%d] is %d",i,arr2[i]);
}
With Pointers
void main()
{
int arr1[5]={1,2,3,4,5};
int arr2[5];
int *m;
int i,*j,k,l=5;
j=arr1;
m=arr2;
func(j,m,l);

17. for(i=0;i<5;i++)
printf("nValue of arr2[%d] is %d",i,arr2[i]);
}
func(int *j, int *m, int l)
{
int i;
for(j=j+4,i=0;i<5;i++,j--,m++)
*m=*j;
}
Chap8[I]b Check similar integers in array
If an array arr contains n elements, then write a program to check if arr[0] =
arr[n-1], arr[1] = arr[n-2] and so on.
This program will have repeated results if the input contains more than 2 same integers
void main()
{
int arr[25];
int i,*j,k;
j=arr;
printf("nInput 25 integers");
for(i=0;i<25;i++,j++)
{
printf("nKey in the %d) value",i+1);
scanf("%d",&*j);
}
for(i=0;i<25;i++)
{
for(k=24;k>i;k--)
if(arr[i]==arr[k])
printf("nArray [%d] = Array[%d]",i,k);
}
}
Chap8[I]c Finding smallest number in array using pointers

18. Find the smallest number in an array using pointers.
Chap8[L]a Initialising 3D array
How will you initialize a three-dimensional array threed[3][2][3]? How will you
refer the first and last element in this array?
void main()
{
int threed[3][2][3]={
{
1,2,3,
4,5,6
},
{
7,8,9,
10,11,12
},
{
13,14,15,
16,17,18
}
};
printf("nFirst element of array is %dnLast element of the array is
%d",threed[0][0][0],threed[2][1][2]);
}

19. hap8[L]b Pick largest number from matrix
Write a program to pick up the largest number from any 5 row by 5 column matrix.
Write a program to obtain transpose of a 4 x 4 matrix. The transpose of a matrix is
obtained by exchanging the elements of each row with the elements of the
corresponding column.
void main()
{
int arr[4][4];
int i,j,a,b,f;
printf("nInput numbers to 4*4 matrix");
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
printf("nKey in the [%d][%d]) value",i+1,j+1);
scanf("%d",&arr[i][j]);
}
}
for(i=0;i<4;i++)
{
for(j=0,f=0;j<4;j++)
{
if(i!=j&&f==0)
continue;
a=arr[i][j];
b=arr[j][i];

20. arr[i][j]=b;
arr[j][i]=a;
f=1;
}
}
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
printf("%d ",arr[i][j]);
printf("n");
}
}
Creating your own strcat()
Creating your own strcat()
void main()
{
char source[]="Folks!";
char target[30]="Hello";
scat(target,source);
printf("nSource string = %s",source);
printf("nTarget string = %s",target);
}
scat(char *m,char *n)
{
char *p;
p=m;
while(*n!='0')
{
if(*m=='0'||m>p+6)
{
*m=*n;
n++;
}
m++;
}

21. *m='0';
}
Very often in fairs we come across a puzzle that contains 15 numbered square
pieces mounted on a frame. These pieces can be moved horizontally or vertically.
A possible arrangement of these pieces is shown below:
As you can see there is a blank at bottom right corner. Implement the following
procedure through a program:
Draw the boxes as shown above. Display the numbers in the above order. Allow
the user to hit any of the arrow keys (up, down, left, or right). If user hits say,
right arrow key then the piece with a number 5 should move to the right and blank
should replace the original position of 5. Similarly, if down arrow key is hit, then
13 should move down and blank should replace the original position of 13. If left
arrow key or up arrow key is hit then no action should be taken. The user would
continue hitting the arrow keys till the numbers aren’t arranged in ascending
order. Keep track of the number of moves in which the user manages to arrange
the numbers in ascending order. The user who manages it in minimum number of
moves is the one who wins. How do we tackle the arrow keys? We cannot receive
them using scanf( ) function. Arrow keys are special keys which are identified by
their ‘scan codes’. Use the following function in your program. It would return the
scan code of the arrow key being hit. Don’t worry about how this function is
written. We are going to deal with it later. The scan codes for the arrow keys are:
up arrow key – 72 down arrow key – 80 left arrow key – 75 right arrow key – 77
/* Returns scan code of the key that has been hit */
#include "dos.h"
getkey( )
{
union REGS i, o ;
while ( !kbhit( ) )
;
i.h.ah = 0 ;
int86 ( 22, &i, &o ) ;
return ( o.h.ah ) ;
}

22. ANS:
#include "dos.h"
void main()
{
void creategrid();
int g,c;
int arr[16]={1,4,15,7,8,10,2,11,14,3,6,13,12,9,5,0};
clrscr();
creategrid();
printarray(arr);
for(g=15,c=0;;)
{
int k,a,b,i;
k=getkey();
if(k==80)
{
if((g-4)<0) a="arr[g-4];" b="arr[g];" k="="72)">15)
continue;
a=arr[g+4];
b=arr[g];
arr[g+4]=b;
arr[g]=a;
go(g);
printf("%d",arr[g]);
go(g+4);
printf("%c%c",0,0);
go(g+4);
c++;
g+=4;
}
if(k==75)
{
if(g==3g==7g==11g==15)
continue;
a=arr[g+1];
b=arr[g];
arr[g+1]=b;
arr[g]=a;
go(g);
printf("%d",arr[g]);
go(g+1);

23. printf("%c%c",0,0);
go(g+1);
c++;
g+=1;
}
if(k==77)
{
if(g==0g==4g==8g==12)
continue;
a=arr[g-1];
b=arr[g];
arr[g-1]=b;
arr[g]=a;
go(g);
printf("%d",arr[g]);
go(g-1);
printf("%c%c",0,0);
go(g-1);
c++;
g-=1;
}
for(i=0;i<15;i++)
{
if(arr[i]!=i+1)
break;
if(arr[i]==(i+1)&&i==14)
{
gotoxy(6,24);
printf("nNumber of moves to complete is %d",c);
exit();
}
}
}
}
go(int g)
{
switch(g)
{
case 0:
gotoxy(8,5);

24. break;
case 1:
gotoxy(12,5);
break;
case 2:
gotoxy(16,5);
break;
case 3:
gotoxy(20,5);
break;
case 4:
gotoxy(8,9);
break;
case 5:
gotoxy(12,9);
break;
case 6:
gotoxy(16,9);
break;
case 7:
gotoxy(20,9);
break;
case 8:
gotoxy(8,13);
break;
case 9:
gotoxy(12,13);
break;
case 10:
gotoxy(16,13);
break;
case 11:
gotoxy(20,13);
break;
case 12:
gotoxy(8,17);
break;
case 13:
gotoxy(12,17);
break;
case 14:
gotoxy(16,17);
break;
case 15:
gotoxy(20,17);
break;
}
}

25. getkey()
{
union REGS i,o;
while(!kbhit())
;
i.h.ah=0;
int86(22,&i,&o);
return(o.h.ah);
}
printarray(int *m)
{
int a,b,i,j;
for(a=5,i=0;a<=17;a+=4,i++)
{
for(b=8,j=0;b<=20;b+=4,j++)
{
gotoxy(b,a);
printf("%d",*(m+(i*4)+j));
}
}
gotoxy(20,17);
printf("%c",0);
}
void creategrid()
{
int a,b;
for(a=3;a<=19;a+=4)
{
for(b=6;b<=22;b++)
{
if(b==6(b-6)%4==0)
{
if(a==3)
{
if(b==6)
{
gotoxy(6,3);
printf("%c",218);
}
else if(b==22)
{

26. gotoxy(22,3);
printf("%c",191);
}
else
{
gotoxy(b,3);
printf("%c",194);
}
}
else if(a==19)
{
if(b==6)
{
gotoxy(6,19);
printf("%c",192);
}
else if(b==22)
{
gotoxy(22,19);
printf("%c",217);
}
else
{
gotoxy(b,19);
printf("%c",193);
}
}
else
{
if(b==6)
{
gotoxy(6,a);
printf("%c",195);
}
else if(b==22)
{
gotoxy(22,a);
printf("%c",180);
}
else
{
gotoxy(b,a);

27. printf("%c",197);
}
}
}
else
{
printf("%c",196);
}
}
}
for(b=6;b<=22;b+=4)
{
for(a=4;a<=18;a++)
{
if((a-3)%4==0)
continue;
else
{
gotoxy(b,a);
printf("%c",179);
}
}
}
}
Write a function to find the norm of a matrix. The norm is defined as the square
root of the sum of squares of all elements in the matrix.
he area of a triangle can be computed
by the sine law when 2 sides of the triangle and the angle between them are
known.

28. Area = (1 / 2 ) ab sin ( angle )
Given the following 6 triangular pieces of land, write a program to find their area
and determine which is largest,
#include math.h (include arrows)
void main()
{
float arr[6][3];
int i,j,d;
float area,c=0;
for(i=0;i<6;i++)
{
for(j=0;j<3;j++)
{
printf("nKey in the [%d][%d] value",i+1,j+1);
scanf("%f",&arr[i][j]);
}
}
for(i=0;i<6;i++)
{
area=(1.0/2.0)*arr[i][0]*arr[i][1]*sin(arr[i][2]);
if(area>c)
{ printf("n1");
c=area;
d=i;
}

29. }
printf("nThe biggest plot of land is plot no. %d with area %f",d+1,c);
}
For the following set of n data points (x, y), compute the correlation coefficient r,
given by
#include math.h (include arrows)
void main()
{
float arr[11][2]={
34.22,102.43,
39.87,100.93,

30. 41.85,97.43,
43.23,97.81,
40.06,98.32,
53.29,98.32,
53.29,100.07,
54.14,97.08,
49.12,91.59,
40.71,94.85,
55.15,94.65
};
int i,j;
float sx=0,sy=0,sx2=0,sy2=0,sxy=0,b,r;
/*calculating summation x*/
for(i=0;i<11;i++)
sx=sx+arr[i][0];
printf("nsummation x is %f",sx);
/*calculating summation y*/
for(i=0;i<11;i++)
sy=sy+arr[i][1];
printf("nsummation y is %f",sy);
/*calculating summation x2*/
for(i=0;i<11;i++)
sx2=sx2+(arr[i][0]*arr[i][0]);
printf("nsummation x2 is %f",sx2);
/*calculating summation y2*/
for(i=0;i<11;i++)
sy2=sy2+(arr[i][1]*arr[i][1]);
printf("nsummation sy2 is %f",sy2);
/*calculating summation xy*/
for(i=0;i<11;i++)
sxy=sxy+(arr[i][0]*arr[i][1]);
printf("nsummation sxy is %f",sxy);
/*calculating bottom part*/
b=(i*sx2-(sx*sx))*(i*sy2-(sy*sy));
printf("nbottom is %f",b);
/*calculating coefficient r*/
r=(sxy-(sx*sy))/(sqrt(b));

31. printf("n The correlation coefficient is %f",r);
}
For the following set of point given by (x, y) fit a straight line given by
y = a + bx
where,
#include math.h (include arrows)
void main()
{
float arr[10][2]={
3.0,1.5,
4.5,2.0,

32. 5.5,3.5,
6.5,5.0,
7.5,6.0,
8.5,7.5,
8.0,9.0,
9.0,10.5,
9.5,12.0,
10.0,14.0
};
int i,j;
float sx=0,sy=0,sx2=0,sxy=0,my,mx,a,b;
/* for(i=0;i<10;i++)
{
for(j=0;j<2;j++)
{
printf("nKey in the [%d][%d] value",i+1,j+1);
scanf("%f",&arr[i][j]);
}
}
*/
/*calculating summation x*/
for(i=0;i<10;i++)
sx=sx+arr[i][0];
/*calculating summation y*/
for(i=0;i<10;i++)
sy=sy+arr[i][1];
/*calculating summation x2*/
for(i=0;i<10;i++)
sx2=sx2+(arr[i][0]*arr[i][0]);
/*calculating summation xy*/
for(i=0;i<10;i++)
sxy=sxy+(arr[i][0]*arr[i][1]);
my=sy/i;
mx=sx/i;
b=((i*sxy)-(sx*sy))/((i*sx2)-(sx*sx));
a=my-(b*mx);

33. printf("nThe value of a is %fnThe value of b is %f",a,b);
}
Creating your own strcat()
void main()
{
char source[]="Folks!";
char target[30]="Hello";
scat(target,source);
printf("nSource string = %s",source);
printf("nTarget string = %s",target);
}
scat(char *m,char *n)
{
char *p;
p=m;
while(*n!='0')
{
if(*m=='0'||m>p+6)
{
*m=*n;
n++;
}
m++;
}
*m='0';
}

34. et Us C / Chapter 8(Arrays)
Exercise [D]
(a) Twenty-five numbers are entered from the keyboard
into an array. The number to be searched is entered
through the keyboard by the user. Write a program to
find if the number to be searched is present in the array
and if it is present, display the number of times it
appears in the array.
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
int i,arr[25],prsnt=0,num;
clrscr();
printf("Please enter 25 numbers: n");
for(i=0;i<25;i++) {
scanf("%d",&arr[i]);
}
printf("nnPlease enter the number to be searched: ");
scanf("%d",&num);

35. for(i=0;i<25;i++) {
if(num==arr[i])
prsnt=prsnt+1;
}
if(prsnt==0) {
printf("nnNumber does not present in the array.n");
}
else {
printf("nnNumber presents in the array.n");
printf("nNumber of times it appears = %d.n",prsnt);
}
getch();
}
---------------------------------------------------------------------------------------------------------------
b) Twenty-five numbers are entered from the keyboard
into an array. Write a program to find out how many of
them are positive, how many are negative, how many are
even and how many odd.
Solution:

36. #include<stdio.h>
#include<conio.h>
void main() {
int i,arr[25],tz=0,tp=0,tn=0;
clrscr();
printf("Enter numbers in the array: n");
for(i=0;i<25;i++) {
scanf("%d",&arr[i]);
if(arr[i]<0){
tn=tn+1;
}
if(arr[i]==0){
tz=tz+1;
}
if(arr[i]>0){
tp=tp+1;
}
}
printf("nnnTotal zeros = %dn",tz);
printf("Total positive numbers = %dn",tp);
printf("Total negative numbers = %dn",tn);

37. getch();
}
----------------------------------------------------------------------------------------------------------------
(c) Implement the Selection Sort, Bubble Sort and
Insertion sort algorithms on a set of 25 numbers. (Refer
Figure 8.11 for the logic of the algorithms)
− Selection sort
− Bubble Sort
− Insertion Sort
Solution:
----------------------------------------------------------------------------------------------------------------
(d) Implement the following procedure to generate prime
numbers from 1 to 100 into a program. This procedure is
called sieve of Eratosthenes.
step 1
Fill an array num[100] with numbers from 1 to 100
step 2

38. Starting with the second entry in the array, set all its
multiples to zero.
step 3
Proceed to the next non-zero element and set all its
multiples to zero.
step 4
Repeat step 3 till you have set up the multiples of all the
non-zero elements to zero
step 5
At the conclusion of step 4, all the non-zero entries left
in the array would be prime numbers, so print out these
numbers.
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
int i,j,a[100];
clrscr();
for(i=0;i<100;i++) {
a[i]=i+1;
}

39. printf("n100 numbers in the array:nn");
for(i=0;i<100;i++) {
printf("%3d ",a[i]);
}
printf("nnafter implementing eratothene's sieve:nn");
for(i=2;i<100;i++) {
for(j=2;j<a[i];j++) {
if(a[i]%j==0)
a[i]=0;
}
}
i=a[0];
for(;i<100;i++) {
printf("%3d ",a[i]);
}
printf("nnprime numbers are: nn");
for(i=a[0];i<100;i++) {

40. if(a[i]!=0)
printf("%3d ",a[i]);
}
getch();
}
---------------------------------------------------------------------------------------------------------------
Exercise [I]
(a) Write a program to copy the contents of one array
into another in the reverse order.
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
int i,j,k,a1[5],a2[5];
clrscr();
for(i=1;i<=5;i++) {
scanf("%d",&a1[i]);
}

41. printf("nnThe elements you enterd are:n");
for(i=1;i<=5;i++) {
printf(" %d",a1[i]);
}
printf("nnElements in reversed order:n");
for(i=5,j=1;i>=1,j<=5;i--,j++) {
k=a1[i];
a2[j]=k;
printf(" %d",a2[j]);
}
getch();
}
---------------------------------------------------------------------------------------------------------------
(b) If an array arr contains n elements, then write a
program to check if arr[0] = arr[n-1], arr[1] = arr[n-2]
and so on.
Solution:
#include<stdio.h>
#include<conio.h>

42. void main() {
int arr[100];
int n,i,f=0;
clrscr();
printf("enter total elements of array(n): ");
scanf("%d",&n);
printf("nnenter "n" elements of array: nn");
for(i=0;i<n;i++) {
scanf("%d",&arr[i]);
}
clrscr();
for(i=0;i<n;i++) {
if(arr[i]==arr[n-(i+1)]) { /* if element is equal, according to the problem,
it will be printed */
f=f+1;
printf("element no: %d = %d ",i,arr[i]);
}
}
if(f==0)
printf("nnNo such element found.n");

43. getch();
}
---------------------------------------------------------------------------------------------------------------
(c) Find the smallest number in an array using pointers.
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
int i,n,*p,*s,a[100];
clrscr();
printf("enter how many numbers you want to save in array: ");
scanf("%d",&n);
printf("nnenter %d number in array:n",n);
for(i=0;i<n;i++) {
scanf("%d",&a[i]);
}

44. clrscr();
printf("array you entered: nn");
for(i=0;i<n;i++) {
printf("%2d ",a[i]);
}
printf("nn");
p=&a[0]; /* first pointer points 0th element */
for(i=0;i<n;i++) {
s=&a[i]; /* second pointer points every element one by one */
if(*p>*s)
/* if first is bigger than second */
*p=*s; /* first becomes second */
s++; /* second is incremented to check with other elements */
}
printf("smallest digit in array is %dn",*p);
getch();
}

45. ----------------------------------------------------------------------------------------------------------------
(d) Write a program which performs the following tasks:
− initialize an integer array of 10 elements in main( )
− pass the entire array to a function modify( )
− in modify( ) multiply each element of array by 3
− return the control to main( ) and print the new array
elements in main( )
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
int i,j,a[10]={1,2,3,4,5,6,7,8,9,10};
modify();
clrscr();
printf("array before modification: nn");
for(i=0;i<10;i++) {
printf(" %d ",a[i]);
}

46. modify(a); /* passing only the name of array */
printf("nnnarray after modification:nn");
for(i=0;i<10;i++) { /* printing the array in main(); */
printf(" %d ",a[i]);
}
getch();
}
modify(int b[10]) {
int c;
for(c=0;c<10;c++) {
b[c]=b[c]*3; /* multiplying each element with 3 */
}
return b[c]; /* returning the whole array to main(); */
}
----------------------------------------------------------------------------------------------------------
(e) The screen is divided into 25 rows and 80 columns.
The characters that are displayed on the screen are

47. stored in a special memory called VDU memory (not to be
confused with ordinary memory). Each character
displayed on the screen occupies two bytes in VDU
memory. The first of these bytes contains the ASCII value
of the character being displayed, whereas, the second
byte contains the colour in which the character is
displayed.
For example, the ASCII value of the character present on
zeroth row and zeroth column on the screen is stored at
location number 0xB8000000. Therefore the colour of
this character would be present at location number
0xB8000000 + 1. Similarly ASCII value of character in row
0, col 1 will be at location 0xB8000000+ 2, and its colour
at 0xB8000000 + 3.
With this knowledge write a program which when
executed would keep converting every capital letter on
the screen to small case letter and every small case
letter to capital letter. The procedure should stop the
moment the user hits a key from the keyboard.
This is an activity of a rampant Virus called Dancing
Dolls. (For monochrome adapter, use 0xB0000000instead
of 0xB8000000).
Solution:
_______________________________________________________________________

48. Exercise [L]
(a) How will you initialize a three-dimensional array
threed[3][2][3]?
How will you refer the first and last element in this
array?
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
/* initialization of a 3 dimensional array */
int threed[3][2][3]={
{
{100,2,3},
{1,2,3}
},
{
{8,5,6},
{4,5,6}
},
{
{7,8,9},
{7,8,200}
}
};
int *f,*l;
clrscr();

49. f=&threed[0][0][0]; /* reference to first element */
l=&threed[2][1][2]; /* reference to second element */
printf("nnfirst element = %d",*f);
printf("nnlast element = %d",*l);
getch();
}
---------------------------------------------------------------------------------------------------------------
(b) Write a program to pick up the largest number from
any 5 row by 5 column matrix.
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
int i,j,a[5][5];
clrscr();
printf("nType the numbers to in matrix:n");

50. for(i=0;i<5;i++) {
for(j=0;j<5;j++) {
scanf("%d",&a[i][j]);
}
}
clrscr();
printf("matrix you entered is:nn");
for(i=0;i<5;i++) {
for(j=0;j<5;j++) {
printf(" %2d ",a[i][j]);
}
printf("n");
}
/* finding the largest number */
for(i=0;i<5;i++) {
for(j=0;j<5;j++) {
if(a[0][0]<a[i][j]) /* if number is larger than first element */

51. a[0][0]=a[i][j]; /* larger number is placed as the first element */
}
}
printf("nnThe largest number in matrix is: %d",a[0][0]);
getch();
}
---------------------------------------------------------------------------------------------------------------
(c) Write a program to obtain transpose of a 4 x 4 matrix.
The transpose of a matrix is obtained by exchanging the
elements of each row with the elements of the
corresponding column.
Solution:
#include<stdio.h>
#include<conio.h>
#define MAX 4
void main() {

52. int i,j,a[4][4],b[4][4];
clrscr();
printf("nenter numbers in 5x5 matrix: nn");
for(i=0;i<MAX;i++) {
for(j=0;j<MAX;j++) {
scanf("%d",&a[i][j]);
}
}
clrscr();
printf("nmatrix you entered is: nn");
for(i=0;i<MAX;i++) {
for(j=0;j<MAX;j++) {
printf("%2d ",a[i][j]);
}
printf("n");
}
/* transpose of matrix */

53. for(i=0;i<MAX;i++) {
for(j=0;j<MAX;j++) {
b[j][i]=a[i][j];
}
}
printf("nn");
/* printing the transpose */
printf("Transpose of matrix is: nn");
for(i=0;i<MAX;i++) {
for(j=0;j<MAX;j++) {
printf("%2d ",b[i][j]);
}
printf("n");
}
getch();
}
----------------------------------------------------------------------------------------------------------------

54. (d) Very often in fairs we come across a puzzle that
contains 15 numbered square pieces mounted on a
frame. These pieces can be moved horizontally or
vertically. A possible arrangement of these pieces is
shown below:
1 4 15 7
8 10 2 11
14 3 6 13
12 9 5
As you can see there is a blank at bottom right corner.
Implement the following procedure through a program:
Draw the boxes as shown above. Display the numbers in
the above order. Allow the user to hit any of the arrow
keys (up, down, left, or right).
If user hits say, right arrow key then the piece with a
number 5 should move to the right and blank should
replace the original position of 5. Similarly, if down
arrow key is hit, then 13 should move down and blank
should replace the original position of 13. If left arrow
key or up arrow key is hit then no action should be
taken.
The user would continue hitting the arrow keys till the
numbers aren’t arranged in ascending order.

55. Keep track of the number of moves in which the user
manages to arrange the numbers in ascending order. The
user who manages it in minimum number of moves is the
one who wins.
How do we tackle the arrow keys? We cannot receive
them using scanf( ) function. Arrow keys are special keys
which are identified by their ‘scan codes’. Use the
following function in your program. It would return the
scan code of the arrow key being hit. Don’t worry about
how this function is written. We are going to deal with it
later. The scan codes for the arrow keys are:
up arrow key – 72 down arrow key – 80 left arrow key – 75
right arrow key – 77
/* Returns scan code of the key that has been hit */
#include "dos.h"
getkey( )
{
union REGS i, o ;
while ( !kbhit( ) ) ;
i.h.ah = 0 ;
int86 ( 22, &i, &o ) ;
return ( o.h.ah ) ;
}

56. Solution:
#include<stdio.h>
#include<conio.h>
#include<dos.h>
/* returns scan code of the key that has been hit */
getkey()
{
union REGS i,o;
while(!kbhit() )
;
i.h.ah=0;
int86(22,&i,&o);
return(o.h.ah);
}
void main() {
int i,j,a[16]={1,4,15,7,8,10,2,11,14,3,6,13,12,9,5,0};
int temp,h,moves=0,won=0;
clrscr();
/****************************************************/
do {
/**************/

57. /* to move up */
/**************/
if(h==72) {
for(i=0;i<16;i++) {
if(a[i]==0){
if(a[0]==0 || a[1]==0 || a[2]==0 || a[3]==0) {
break;
}
temp=a[i];
a[i]=a[i-4];
a[i-4]=temp;
moves=moves+1;
break;
}
}
}
/****************/
/* to move left */
/****************/
if(h==75) {
for(i=0;i<16;i++) {
if(a[i]==0){
if(a[0]==0 || a[4]==0 || a[8]==0 || a[12]==0) {
break;
}
temp=a[i];

58. a[i]=a[i-1];
a[i-1]=temp;
moves=moves+1;
break;
}
}
}
/****************/
/* to move down */
/****************/
if(h==80) {
for(i=0;i<16;i++) {
if(a[i]==0){
if(a[12]==0 || a[13]==0 || a[14]==0 || a[15]==0) {
break;
}
temp=a[i];
a[i]=a[i+4];
a[i+4]=temp;
moves=moves+1;
break;
}
}
}
/*****************/
/* to move right */
/*****************/
if(h==77) {

59. for(i=0;i<16;i++) {
if(a[i]==0) {
if(a[3]==0 || a[7]==0 || a[11]==0 || a[15]==0 ) {
break;
}
temp=a[i];
a[i]=a[i+1];
a[i+1]=temp;
moves=moves+1;
break;
}
}
}
/***********************************************************/
/**********************************/
/* printing the puzzle with boxes */
/**********************************/
printf("n%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%cn",218,196,196,196,194,196,196,196,194,
196,196,196,194,196,196,196,191);
for(i=0;i<=15;i++) {
printf("%c",179);
if(a[i]==0) {
printf("%c ",32); /* printing a blank space in the puzzle */
}

60. if(a[i]!=0)
printf(" %2d",a[i]);
if(a[i]==a[3] || a[i]==a[7] || a[i]==a[11] || a[i]==a[15])
printf("%c",179);
if(i==3||i==7||i==11)
printf("n%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%cn",195,196,196,196,197,196,196,196,197,
196,196,196,197,196,196,196,180);
if(a[0]==1 && a[1]==2 && a[2]==3 && a[3]==4 && a[4]==5 && a[5]==6
&&a[6]==7 && a[7]==8 && a[8]==9 && a[9]==10 && a[11]==12 && a[12]==13
&& a[13]==14 && a[14]==15 && a[15]==0 ) {
won=1;
}
}
printf("n%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%cn",192,196,196,196,193,196,196,196,193,
196,196,196,193,196,196,196,217);
/***************************************************/
if(won==1) {
printf("nntCongratulations! you have won.");
break;
}
/**********************************/
/* to print instructions for user */
/**********************************/
printf("nnnnnn Total Moves: %dtttt Use arrow keys to move blank:nn",moves);

61. printf("tttttt %c to move upn",30);
printf("tttttt %c to move downn",31);
printf("tttttt %c to move leftn",17);
printf("tttttt %c to move rightn",16);
/****************************************************/
/**********************/
/* to take user input */
/**********************/
h=getkey();
clrscr();
/****************************************************/
}while(h==72 || h==75 || h==77 ||h==80);
getch();
}
-----------------------------------------------------------------------------------------------------------------
(e) Those readers who are from an Engineering/Science
background may try writing programs for following
problems.
(1) Write a program to add two 6 x 6 matrices.

62. (2) Write a program to multiply any two 3 x 3 matrices.
(3) Write a program to sort all the elements of a 4 x 4
matrix.
(4) Write a program to obtain the determinant value of a
5 x 5 matrix.
Solution:
--------------------------------------------------------------------------------------------------------------
(j) Write a program that interchanges the odd and even
components of an array.
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
int i,j,a[6],even,temp;
clrscr();
printf("enter the numbers: nn");
for(i=0;i<6;i++) {
scanf("%d",&a[i]);

63. }
clrscr();
printf("narray without exchanging even and odd numbers:nn");
for(i=0;i<6;i++) {
printf("%2d ",a[i]);
}
printf("nnarray after exchanging even and odd numbers: nn");
for(i=0;i<6;i++) {
for(j=i+1;j<6;j++) {
/* if one element is even and another after that is odd
,they will be exchanged */
if((a[i]%2)!=0 && (a[j]%2)==0) {
temp=a[j];
a[j]=a[i];
a[i]=temp;
}
}
}
for(i=0;i<6;i++) {

64. printf("%2d ",a[i]);
}
getch();
}
--------------------------------------------------------------------------------------------------------------
(k) Write a program to find if a square matrix is
symmetric.
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
int i,j,r,c,sym;
int a[100][100],b[100][100];
clrscr();
printf(" enter number of rows of matrix: ");
scanf("%d",&r);
printf("nnenter number of columns of matrix: ");
scanf("%d",&c);

65. clrscr();
printf("enter the elements in matrix: n");
for(i=0;i<r;i++) {
for(j=0;j<c;j++) {
scanf("%d",&a[i][j]);
}
}
clrscr();
printf("nmatrix you entered isnn");
for(i=0;i<r;i++) {
for(j=0;j<c;j++) {
printf("%d ",a[i][j]);
}
printf("n");
}
printf("nntranspose of matrix is nn");
for(i=0;i<r;i++) {

66. for(j=0;j<c;j++) {
b[j][i]=a[i][j];
}
}
for(i=0;i<r;i++) {
for(j=0;j<c;j++) {
printf("%d ",b[i][j]);
}
printf("n");
}
/* finding if square matrix is equal to it's transpose to be symmetric */
for(i=0;i<r;i++) {
for(j=0;j<c;j++) {
if(a[i][j]!=b[i][j])
sym=1;
}
}

67. if(sym==1)
printf("nSquare matrix is not symmetric.n");
else
printf("nSquare matrix is symmetric.n");
getch();
}
----------------------------------------------------------------------------------------------------------------
(l) Write a function to find the norm of a matrix. The
norm is defined as the square root of the sum of squares
of all elements in the matrix.
Solution:
#include<stdio.h>
#include<conio.h>
#include<math.h>
void main() {
int i,j,r,c,a[100][100];
int norm=0,sum=0;
clrscr();
printf("nEnter the number of rows: ");
scanf("%d",&r);

68. printf("nnEnter the number of coloumns: ");
scanf("%d",&c);
clrscr();
printf("Enter elements of %d x %d array: nn",r,c);
for(i=0;i<r;i++) {
for(j=0;j<c;j++) {
scanf("%d",&a[i][j]);
}
}
clrscr();
printf("nmatrix you entered is: nn");
for(i=0;i<r;i++) {
for(j=0;j<c;j++) {
printf("%2d ",a[i][j]);
}
printf("n");
}
/* norm of the matrix */

69. for(i=0;i<r;i++) {
for(j=0;j<c;j++) {
sum=sum+(a[i][j]*a[i][j]);
}
}
norm=sqrt(sum);
printf("nNorm of matrix = %d",norm);
getch();
}
----------------------------------------------------------------------------------------------------------------
(m) Given an array p[5], write a function to shift it
circularly left by two positions. Thus, if p[0] = 15, p[1]=
30, p[2] = 28, p[3]= 19 and p[4] = 61 then after the shift
p[0] = 28, p[1] = 19, p[2] = 61, p[3] = 15 and p[4] = 30.
Call this function for a (4 x 5 ) matrix and get its rows
left shifted.
Solution:
#include<stdio.h>

70. #include<conio.h>
void main() {
int i,j,p[]={15,30,28,19,61};
int a[4][5];
clrscr();
printf("Array before shift:nn");
for(i=0;i<5;i++) {
printf("%2d ",p[i]);
}
func(p);
printf("nnArray after shift:nn");
for(i=0;i<5;i++) {
printf("%2d ",p[i]);
}
printf("nnnenter the elements of 4x5 matrix: nn");
for(i=0;i<4;i++) {
for(j=0;j<5;j++) {

71. scanf("%d",&a[i][j]);
}
}
clrscr();
printf("matrix you enterd before shift: nn");
for(i=0;i<4;i++) {
for(j=0;j<5;j++) {
printf("%2d ",a[i][j]);
}
printf("n");
}
printf("nnafter shift:nn");
/* shift the rows of matrix */
for(i=0;i<4;i++) {
func(a[i]);
}

72. for(i=0;i<4;i++) {
for(j=0;j<5;j++) {
printf("%2d ",a[i][j]);
}
printf("n");
}
getch();
}
func(int q[5]) {
int a,t1,t2,t3;
t1=q[0];
t2=q[1];
q[0]=q[2];
q[1]=q[3];
q[2]=q[4];
q[3]=t1;
q[4]=t2;
return q[5];
}

73. ----------------------------------------------------------------------------------------------------------
(n) A 6 x 6 matrix is entered through the keyboard and
stored in a 2-dimensional array mat[7][7]. Write a
program to obtain the Determinant values of this matrix.
Solution:
----------------------------------------------------------------------
--------
(o) For the following set of sample data, compute the
standard deviation and the mean.
-6, -12, 8, 13, 11, 6, 7, 2, -6, -9, -10, 11, 10, 9, 2
Solution:
#include<stdio.h>
#include<conio.h>
#include<math.h>
void main() {
int a[15]={-6,-12,8,13,11,6,7,2,-6,-9,-10,11,10,9,2};
int i,j;
float temp,sd,sum=0,mean,x;
clrscr();

74. printf("ndata set: nn");
for(i=0;i<15;i++) {
printf(" %3d ",a[i]);
}
printf("n");
for(i=0;i<15;i++) {
sum=sum+a[i]; /* adding all the numbers */
}
mean=sum/15; /* calculating the mean */
/* computing standard deviation */
for(i=0;i<15;i++) {
a[i]=pow((a[i]-mean),2);
x=x+a[i];
}
temp=x/15;
sd=sqrt(temp);

75. printf("nnttmean= %fnttstandard deviation = %fn",mean,sd);
getch();
}
--------------------------------------------------------------------------------------------------------------
(p) The area of a triangle can be computed by the sine
law when 2 sides of the triangle and the angle between
them are known.
Area = (1 / 2 ) ab sin ( angle )
Given the following 6 triangular pieces of land, write a
program to find their area and determine which is
largest,
Plot No.
a
b
angle
137.4
80.9
0.78

76. 155.2
92.62
0.89
149.3
97.93
1.35
160.0
100.25
9.00
155.6
68.95
1.25
149.7

77. 120.0
1.75
Solution:
#include<stdio.h>
#include<conio.h>
#include<math.h>
void main() {
float a[6][3]={ {137.4, 80.9, 0.78},
{155.2, 92.62, 0.89},
{149.3, 97.93, 1.35},
{160.0, 100.25, 9.00},
{155.6, 68.95, 1.25},
{149.7, 120.0, 1.75} };
float big=0,area;
int sr=0,i;
clrscr();
for(i=0;i<6;i++) {
area=(1.0/2.0)*a[i][0]*a[i][1]*sin(a[i][2]);
if(area>big) {
big=area;
sr=i;

78. }
}
printf("nnPlot no. %d is the biggest.n",sr);
printf("nArea of plot no. %d = %fn",sr,big);
getch();
}
-
------------------------------------------------------------------------------------------------------------
(q) For the following set of n data points (x, y), compute
the correlation coefficient r,
x
y
34.22
102.43
39.87

79. 100.93
41.85
97.43
43.23
97.81
40.06
98.32
53.29
98.32
53.29
100.07
54.14
97.08
49.12
91.59

80. 40.71
94.85
55.15
94.65
Solution:
#include<stdio.h>
#include<conio.h>
#include<math.h>
void main() {
float a[][2]={ {34.22,102.43},
{39.87,100.93},
{41.85,97.43},
{43.23,97.81},
{40.06,98.32},
{53.29,98.32},
{53.29,100.07},
{54.14,97.08},
{49.12,91.59},
{40.71,94.85},
{55.15,94.65} };
int i,n=0;
float x2,y2,x,y,x_y,n_x2,n_y2,r;

81. clrscr();
for(i=0;i<11;i++) {
x2= x2 + ( a[i][0] * a[i][0] ); /* computing square of x */
y2= y2 + ( a[i][1] * a[i][1] ); /* computing square of y */
x= x + a[i][0]; /* computing total of x */
y= y + a[i][1]; /* computing total of y */
x_y= x_y + ( a[i][0] * a[i][1] ); /* computing total of x * y */
n++;
}
n_x2= n * x2;
n_y2= n * y2;
r= ( x_y - x*y )/sqrt((n_x2-x2) * (n_y2-y2));
printf(" sum of square of x = %fnn",x2);
printf(" sum of square of y = %fnn",y2);
printf(" sum of x = %fnn",x);
printf(" sum of y = %fnn",y);
printf(" sum of x * y = %fnn",x_y);
printf(" sum of n*x2 = %fnn",n_x2);
printf(" sum of n*y2 = %fnn",n_y2);

82. printf("nnnCorrelation cofficient = %fn",r);
getch();
}
-------------------------------------------------------------------------------------------------------------
(r) For the following set of point given by
(x, y) fit a straight line given by
y = a + bx
x
y
3.0
1.5
4.5
2.0
5.5
3.5

83. 6.5
5.0
7.5
6.0
8.5
7.5
8.0
9.0
9.0
10.5
9.5
12.0
10.0
14.0
Solution:
#include<stdio.h>
#include<conio.h>

84. #include<math.h>
void main() {
float data[][2]= { {3.0,1.5},
{4.5,2.0},
{5.5,3.5},
{6.5,5.0},
{7.5,6.0},
{8.5,7.5},
{8.0,9.0},
{9.0,10.5},
{9.5,12.0},
{10.0,14.0} };
int i,n=0;
float sx,sy,x2,y2,xy,a,b,Y;
clrscr();
for(i=0;i<10;i++) {
sx = sx + data[i][0];
sy = sy + data[i][1];
x2= x2 + ( data[i][0] * data[i][0] );
y2= y2 + ( data[i][1] * data[i][1] );
xy = xy + ( data[i][0] * data[i][1] );

85. n++;
}
printf(" sum of x = %fn",sx);
printf(" sum of y = %fn",sy);
printf(" sum of x2 = %fn",x2);
printf(" sum of y2 = %fn",y2);
printf(" sum of x*y = %fn",xy);
printf(" total number = %dn",n);
b = ( (n*xy) - (sx*sy) ) / ( n*x2 - (sx*sx) );
a = (sy/n) - b*(sx/n);
Y= a + b*sx ;
printf("nnvalue of a = %fnn",a);
printf("value of b = %fnn",b);
printf(" Y = %f nn",Y);
getch();
}
-------------------------------------------------------------------------------------------------------------

86. (s) The X and Y coordinates of 10 different
points are entered through the keyboard.
Write a program to find the distance of
last point from the first point (sum of
distance between consecutive points).
Solution:
#include<stdio.h>
#include<conio.h>
void main() {
float a[10][2],sx,sy;
int i;
clrscr();
for(i=0;i<10;i++) {
printf("Enter coordinates of point number %d:nn",i+1);
printf("Value of X coordinate: ");
scanf("%f",&a[i][0]);
printf("nValue of Y coordinate: ");
scanf("%f",&a[i][1]);

87. clrscr();
}
for(i=0;i<10;i++) {
if(i>0 && i<10-1) {
sx = sx + a[i][0];
sy = sy = a[i][1];
}
}
printf(" First coordinate: X = %ftY = %fnn",a[0][0],a[0][1]);
printf(" Last coordinate: X = %ftY = %fnn",a[9][0],a[9][1]);
printf("nDistance between them: X = %ftY = %fn",sx,sy);
getch();
}