1. An array is a group of variables of the same type referred to by a common name. Arrays can have one or more dimensions. 2. A one-dimensional array stores elements in contiguous memory locations. Elements are accessed using an index number within square brackets. 3. Common array operations include initializing values, accessing individual elements, searching for elements, finding the maximum/minimum value, and performing element-wise operations on multiple arrays.

1. Structured Programming Language
1 D Array
Mohammad Imam Hossain,
Lecturer, CSE, UIU

2. Array
• An array is a group of like-typed variables that are
referred to by a common name.
• Arrays of any type (int, char, float, double etc.) can be
created and may have one or more dimensions.
• Arrays form a convenient way to handle groups of
related data.

3. Array Element
• An individual variable in the array is called an array element.
• All the array elements must be of the same type and same
storage class.
• Each array element is referred to by specifying the array name
followed by one or more subscripts, with each subscript
enclosed in square brackets.
• Each subscript must be expressed as a nonnegative integer.
• The value of each subscript can be expressed as an integer
constant, an integer variable or a more complex integer
expression.

4. 1 Dimensional Array
• A one-dimensional array is a list of variables that are
all of the same type and are accessed through a
common name.
• C stores one-dimensional arrays in one contiguous
memory location with the first element at the lowest
address.

5. Declaring 1 D Array
type var_name[size];
• type is a valid C data type.
• var_name is the name of the array.
• size specifies the number of elements in
the array.

6. Declaring 1 D Array
type var_name[size];
• type is a valid C data type.
• var_name is the name of the array.
• size specifies the number of elements in
the array.
int x[100]; ///x is a 100 element integer array
char text[80]; ///text is an 80 element character array
#define SIZE 20
…….
float myarray[SIZE]; ///myarray is a 20 element floating-point array

7. 1 D Array Elements
• 1st element : x[0]
• 2nd element : x[1]
• 3rd element : x[2]
• 5th element : x[4]
int x[5];
⋮
⋮
x[0] x[1] x[2] x[3] x[4]

8. 1 D Array Elements
• 1st element : x[0]
• 2nd element : x[1]
• 3rd element : x[2]
• 5th element : x[4]
int x[5];
⋮
⋮
Element No i Index No i-1
x[0] x[1] x[2] x[3] x[4]

9. 1 D Array Initialization
int x[5] = { 1, 2, 3, 4, 5};
Similarly,
x[0] x[1] x[2] x[3] x[4]
1 2 3 4 5
float arr[6]={0, 0.25, 0, -0.50, 0, 0};
char color[ ]={'R', 'G', 'B'};
• The array size need not be specified explicitly when initial
values are included as a part of an array definition.
• The array size will automatically be set equal to the
number of initial values included within the definition.

10. Assigning Values to Array Elements
int x[5] = { 1, 2, 3, 4, 5};
x[0] x[1] x[2] x[3] x[4]
1 2 3 4 5
x[2] = 7;

11. Assigning Values to Array Elements
int x[5] = { 1, 2, 3, 4, 5};
x[0] x[1] x[2] x[3] x[4]
1 2 3 4 5
x[0] x[1] x[2] x[3] x[4]
1 2 7 4 5
x[2] = 7;

12. Printing Array Elements
int x[5] = { 1, 2, 3, 4, 5};
x[0] x[1] x[2] x[3] x[4]
1 2 3 4 5
printf (“ % d “ , x[2] ) ; ///3

13. Problem
• Write a program that will declare a 10 elements array
and saves the value of squares from 1 to 10 to those
10 array elements.

14. Problem
• Write a program that will declare a 10 elements array
and saves the value of squares from 1 to 10 to those
10 array elements.
x[0] x[1] x[2] x[3] x[4]
1 4 9 16 25
x[5] x[6] x[7] x[8] x[9]
36 49 64 81 100

15. Solution
#include<stdio.h>
int main()
{
return 0;
}

16. Solution
#include<stdio.h>
#define SIZE 10
int main()
{
int sqrs[SIZE], i;
return 0;
}

17. Solution
#include<stdio.h>
#define SIZE 10
int main()
{
int sqrs[SIZE], i;
///assigning values to array elements
for(i=0; i<=SIZE-1; i++){
sqrs[i]=(i+1)*(i+1);
}
return 0;
}

18. Solution
#include<stdio.h>
#define SIZE 10
int main()
{
int sqrs[SIZE], i;
///assigning values to array elements
for(i=0; i<=SIZE-1; i++){
sqrs[i]=(i+1)*(i+1);
}
///showing the values of array elements
for(i=0; i<=SIZE-1; i++){
printf("%d th element: %dn", i, sqrs[i]);
}
return 0;
}

19. scanf for 1 D Array
• Using scanf you can give input values to specific array
elements.
x[0] x[1] x[2] x[3] x[4]
1 2 3 4 5
scanf("%d", &x[2]); ///let, user gives input 100
x[0] x[1] x[2] x[3] x[4]
1 2 100 4 5

20. Sample code
#include<stdio.h>
int main()
{
int arr[10]={1,2,3,4,5,6,7,8,9,10};
int i;
for(i=0;i<10;i+=2){
scanf("%d", &arr[i] );
}
for(i=0;i<10;i++){
printf("%d ", arr[i] );
}
return 0;
}

21. Note
• Single operations
which involve entire
arrays are not
permitted in C.
• So in C, you can’t
assign one entire
array to another.
#include<stdio.h>
int main()
{
int a1[10],a2[10];
int i;
for(i=0;i<10;i++){
scanf("%d", &a1[i] );
}
a2=a1; ///error
return 0;
}

22. Sample code
///sample code to copy one array into another
#include<stdio.h>
int main()
{
int a1[5],a2[5];
int i;
for(i=0;i<5;i++){
scanf("%d", &a1[i] );
}
///can’t write a2=a1;
for(i=0;i<5;i++){
a2[i]=a1[i];
}
///showing outputs
for(i=0;i<5;i++){
printf("%d ",a2[i]);
}
return 0;
}

23. Problem
• Write a program to search an element from array
elements.

24. Sample code
#include<stdio.h>
#define SIZE 1000
int main()
{
int arr[SIZE];
int sz,element;
printf("Please enter the number of elements of the array: ");
scanf("%d",&sz);
int i;
for(i=0;i<sz;i++){
scanf("%d",&arr[i]);
}
printf("Please enter the element to search for: ");
scanf("%d", &element);
for(i=0;i<sz;i++){
if(arr[i]==element){
printf("Yes");
break;
}
}
if(i==sz) printf("No");
return 0;
}

25. Problem
• Write a program to find the maximum element of an
array containing positive numbers.

26. Sample code
#include<stdio.h>
#define SIZE 1000
int main()
{
int arr[SIZE];
int sz, max_el=0;
printf("Please enter the number of elements of the array: ");
scanf("%d",&sz);
int i;
for(i=0;i<sz;i++){
scanf("%d",&arr[i]);
}
for(i=0;i<sz;i++){
if(arr[i]>max_el){
max_el=arr[i];
}
}
printf("The maximum value is %dn", max_el);
return 0;
}

27. Problem
• Write a program to save an array in reverse order
into another array.

28. Sample code
#include<stdio.h>
int main()
{
int arr[5]={1,2,3,4,5};
int rev_arr[5];
int i;
for(i=0;i<5;i++){
rev_arr[i]=arr[5-i-1];
}
for(i=0;i<5;i++) printf("%d ",rev_arr[i]);
return 0;
}

29. Problem
• Write a program to calculate the sum of two 1 D
array (element wise) of exactly same size.

30. Sample code
#include<stdio.h>
int main()
{
int a1[5]={1,2,3,4,5};
int a2[5]={5,4,3,2,1};
int sum[5];
int i;
for(i=0;i<5;i++){
sum[i]=a1[i]+a2[i];
}
for(i=0;i<5;i++) printf("%d ",sum[i]);
return 0;
}

31. Problem
• Write a program to right rotate an array. Take input
the amount to rotate right.

32. Sample code
#include<stdio.h>
#define SIZE 7
int main()
{
int arr[SIZE]={1,2,3,4,5,6,7};
int r_rotate;
printf("Enter the amount to rotate right: ");
scanf("%d",&r_rotate);
int i;
for(i=SIZE-1;i>=r_rotate;i--){
arr[i]=arr[i-r_rotate];
}
for(i=0;i<r_rotate;i++){
arr[i]=0;
}
for(i=0;i<SIZE;i++) printf("%d ",arr[i]);
return 0;
}

33. Problem
• Write a program to separate the even and odd
elements of an array into two other arrays.

34. Sample code
#include<stdio.h>
#define SIZE 7
int main()
{
int arr[SIZE]={1, 2, 3, 4, 5, 6, 7};
int even[SIZE],odd[SIZE];
int i,even_sz=0,odd_sz=0;
for(i=0;i<SIZE;i++){
if(arr[i]%2==0){
even[even_sz]=arr[i];
even_sz++;
}
else{
odd[odd_sz]=arr[i];
odd_sz++;
}
}
printf("Even Array: "); ///showing the even numbers
for(i=0;i<even_sz;i++) printf("%d ",even[i]);
printf("nOdd Array: "); ///showing the odd numbers
for(i=0;i<odd_sz;i++) printf("%d ",odd[i]);
return 0;
}

35. References:
• Teach Yourself C, 3rd edition
Section: 5.1
• Schaum’s Outline,3rd edition
Section: 9.1, 9.2