14. Contd.
08/23/1514
•For example, the array marks can be initialized while declaring
using this statement.
int marks[5]={51,62,43,74,55};
•The elements of the array marks can be referred to as marks [0],
marks [1],marks [2], marks [3] and marks [4], respectively.
•The memory representation of the array marks is shown in Figure.
As each element is of the type int (that is, 2 bytes long), the array
marks occupies ten contiguous bytes in memory and these bytes are
reserved in the memory at the compile-time.
15. Problem
double percentage[50];
If this array percentage is stored in memory starting from
address 3000. then what will be the address of
percentage[20] element.
08/23/1515
Ans: 3000+20*8= 3160
What will be size of array?
Ans:400
17. Example 1: Find the minimum
of a set of 10 numbers
#include <stdio.h>
main(){
int a[10], i, min;
printf(“Enter 10 numbers:”);
for (i=0; i<10; i++)
scanf (“%d”, &a[i]);
min = a[0];
for (i=1; i<10; i++){
if (a[i] < min)
min = a[i];
}
printf (“n Minimum is %d”, min);
}
08/23/1517
18. Alternate Version1 for last
problem
#include <stdio.h>
#define SIZE 10
main(){
int a[SIZE], i, min;
printf(“Enter 10 numbers:”);
for (i=0; i< SIZE; i++)
scanf (“%d”, &a[i]);
min = a[0];
for (i=1; i< SIZE; i++){
if (a[i] < min)
min = a[i];
}
printf (“n Minimum is %d”, min);
} 08/23/1518
19. Alternate Version2 for last
problem
#include <stdio.h>
main(){
int a[500], i, min;
printf(“Enter number of elements:”);
scanf(“%d”,&n);
printf(“Enter n numbers:”);
for (i=0; i< n; i++)
scanf (“%d”, &a[i]);
min = a[0];
for (i=1; i< n; i++){
if (a[i] < min)
min = a[i];
}
printf (“n Minimum is %d”, min);
}
08/23/1519
20. Things you can not do with
array
• You cannot use = to assign one array variable to another
E.g. a = b; is illegal where a and b are arrays.
• You cannot use == to directly compare array variables
e.g. if (a = = b) is illegal.
• You cannot use directly scanf or printf arrays
printf (“…….”, a); is illegal.
08/23/1520
21. How to copy the elements of
one array to another?
By copying individual elements
for (j=0; j<25; j++)
a[j] = b[j];
08/23/1521
22. How to read the elements of an
array?
• By reading them one element at a time
for (j=0; j<25; j++)
scanf (“%f”, &a[j]);
• The ampersand (&) is necessary.
08/23/1522
24. Problem- linear search in one-D array
Write a program that asks the user to enter n integers of an
array and an integer x. The program must search if n is in the
array of n integers.
Following is the sample output
08/23/1524
25. void main() {
int array[100], search, c, n;
printf("Enter the number of elements in arrayn"); scanf("%d",&n);
printf("Enter %d integer(s)n", n);
for (c = 0; c < n; c++)
scanf("%d", &array[c]);
printf("Enter the number to searchn");
scanf("%d", &search);
for (c = 0; c < n; c++) {
if (array[c] == search){ /* if required element found */
printf("%d is present at location %d.n", search, c+1);
break;
}
}
if (c == n)
printf("%d is not present in array.n", search);
} 08/23/1525
26. Sort one-D array and find its
median
void main(){
int i,j,n,temp,arr[100];
printf(“Enter n:”);
for(i=0;i<n;i++)
scanf(“%d”,&arr[i]);
for(i=0; i<n-1; i++) {
for(j=i+1; j<n; j++) {
if(arr[i] > arr[j]) { // swap elements
temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
}
if(n%2==0) // if there is an even number of elements, median will be mean of the two elements in the middle
printf(“median is=%d”,(x[n/2] + x[n/2 - 1]) / 2.0);
else //else return the element in the middle
printf(“median is=%d”,x[n/2]);
}
30. Initialization of Two-
Dimensional Array
Like a single-dimensional array, a two-dimensional array can
also be declared and initialized at the same time.
To understand the concept of two-dimensional array
initialization, consider this statement.
int a[3] [2]={
{101,51},
{l02,67},
{l03,76} }
08/23/1530
31. Initialization of Two-
Dimensional Array
In last statement, an array of type int having three rows and two
columns is declared and initialized.
This type of initialization is generally used to increase the readability.
However, the array a can also be initialized using this statement.
int a[] [2]={101,51,l02,67,l03,76};
In this statement, the first two elements are stored in the first row,
next two in the second row and so on.
Note that while initializing a two-dimensional array, mentioning the
row size is optional, however, the column size must be specified.
08/23/1531
33. How to read the elements of a 2-D
array?
• By reading them one element at a time
for (i=0; i<nrow; i++)
for (j=0; j<ncol; j++)
scanf (“%f”, &a[i][j]);
• The ampersand (&) is necessary.
08/23/1533
37. 08/23/1537
•int a[] [2]={101,51,l02,67,l03,76};
•For example, the elements of array are referred to as a [0] [0], a [0] [1], a [1] [0],
a [1] [1], a [2] [0] and a [2] [1] respectively.
•Generally, two-dimensional arrays are represented with the help of a matrix.
•However, in actual implementation, two-dimensional arrays are always allocated
contiguous blocks of memory.
•Figure shows the matrix and memory representation of two-dimensional array a.
43. Indenting C Programs
Why Indentation is Important: Good style is about making
your program
1. Clear
2. Understandable and
3. Easily modifiable.
Use proper comment in program for better readability.
There are so many Indenting Styles like Kernel style, K&R style
and ANSI Style.
We will follow ANSI Style(also known as Allman style).
08/23/1543
44. Rules of ANSI Style
This style puts the brace associated with a control statement(if,while,for, etc.) on the
next line, indented to the same level as the control statement.
Statements within the braces are indented to the next level(indented by one tab).
Following is the code segment without proper indentation
while (x == y) {
printf(“x and y are same”);
printf(“Next What to Do!”);
}
Same code segment in ANSI style would be
while (x == y)
{
printf(“x and y are same”);
printf(“Next What to Do!”);
}
08/23/1544
45. Some Examples of Bad vs Good coding
style
Code without proper indentation:
void main(){
int a=40000,b=20000;
if(a<b) printf(“Wow!”);
else printf(“Really!”);
}
Same code segment in ANSI style would be
void main()
{
int a=40000,b=20000;
if(a<b) // comparison of a and b
printf(“Wow!”);
else
printf(“Really!”);
}
}
08/23/1545
46. Some Examples of Bad vs Good coding
style
Code without proper indentation:
#include<stdio.h>
void main(){
int row,col;
for (row=1; row<=5; row++) {
for (col=1; col<=5; col++) {
if(row==1 || row==5 || col==1 || col==5)
printf("*");
else
printf(" ");
}
printf("n");
}
}
08/23/1546
47. Some Examples of Bad vs Good coding
style
Same code segment in ANSI style would be:
void main()
{
int row,col;
for (row=1; row<=5; row++) //outer Loop
{
for (col=1; col<=5; col++) //Inner Loop
{
if(row==1 || row==5 || col==1 || col==5)
printf("*");
else
printf(" ");
}
printf("n");
}
}
08/23/1547
