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C Program to reverse the first half of array elements

Get array size n and n elements of array, then reverse the first n/2 elements.

Sample Input 1:

5 5 7 9 3 1

Sample Output 1:

7 5 9 3 1

Program or Solution

					    
							
#include <stdio.h>
#include <stdlib.h>


int main(void)

{
	
	int *a,n,i,j,temp;

	printf("Enter size of array:");
	scanf("%d",&n);

	a=malloc(sizeof(int)*n);

	printf("Enter %d Elements:",n);
	for(i=0;i<n;i++)

	{

		scanf("%d",&a[i]);

	}

	
		
	for(i=0,j=n/2-1;i<j;i++,j--)
	
	{

		temp=a[i];
		a[i]=a[j];
		a[j]=temp;
	}

	printf("After reversing the first half:\n");
	for(i=0;i<n;i++)

	{

		printf("%d",a[i]);

	}

	
	return 0;

}
					    
					

Program Explanation

initialize i to first location of array and j to middle location of array using i=0 j=n/2-1

swap the elements in location i and j, then increment i by 1 and decrement j by 1.

t=a[i] a[i]=a[j] a[j]=temp repeat the above step till i is less than j