Program to reverse an array

In this example, We will learn a program to reverse an array. For this, we must have knowledge in following topics

• For Loop
• Array

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Algorithm

This is the algorithm of this program

Step 1: Start
Step 2: Initialize variables c, d, n, a and b
Step 3: Take input from user and stored in n
Step 4: Assign c = 0
Step 5: Repeat this step until c < n
        Take input from user and store in c index of a i.e a[c]
        Increase c by 1
Step 6: Assign c = n-1 and d = 0
Step 7: Repeat this step unitl c >= 0
        Copy the value of a[c] to b[d]
        Decrease c by 1 and Increase d by 1
Step 8: Assign c = 0
Step 9: Repeat this step until c < n
        Copy the value of b[c] to a[c]
        Increase c by 1
Step 8: Assign c = 0
Step 10: Repeat this step until c < n
        Print a[c]
        Increase c by 1
Step 11: End

Flowchart

This is the flowchart of this program

CODE: Program to reverse an array

Now, We will see the code to reverse an array.

#include<stdio.h>

int main(){
    
    int c, d, n, a[100], b[100];
    printf("\nEnter number of elements in array :");
    scanf("%d", &n);

    printf("\nEnter %d elements\n", n);
    for(c = 0; c < n; c++)
        scanf("%d", &a[c]);

    /*
        temporarily storing 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 to reverse it.
    */
    for(c = 0; c < n; c++)
        a[c] = b[c];


    printf("\n Resultant array is: ");
    for(c = 0; c < n; c++)
        printf("%d\t", a[c]);
        

    return 0;
}

The output of above program is

Enter number of elements in array :5

Enter 5 elements
1
2
3
4
5

 Resultant array is: 5  4       3       2       1