C Program to Search an Element in an array using Pointers

Description

Get an element and find the location of element in array, print -1 if element is not found.
Input:
5
5 7 9 3 1
9
Output:
2
Input:
5
5 7 9 3 1
4
Output:
-1

Solution

#include <stdio.h>


#include <stdlib.h>
int main(void)

{
	
	int n,i,pos=-1,*a,element;

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

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

	{

		scanf("%d",a+i);

	}

	printf("Enter a element to find:");
	scanf("%d",&element);

	
	for(i=0;i<n;i++)
	
	{

		if(*(a+i)==element)
		{
			pos=i;
			break;
		}
	}

	printf("%d is in %d",element,pos);	
	return 0;

}

Explanation

calloc() is predefined function allocates memory of specified bytes.
Number of bytes is specified as (4,n), it means n 4 bytes. Since we are using integers, specified as 4bytes.

*a denotes first four bytes,  *(a+1) denotes second four bytes, *(a+2) denotes third four bytes and so on.,

i is initialized to 0 and incremented by 1 at each iteration of both the for loops.

First for loop reads n input numbers from user and stores them in array a[] from location 0 to n-1

using Second for loop the element is searched in each location from 0 to  the location of element or location n-1.

if element is found in a location that location i is stored as pos and exit from the for loop using break statement. 

if element is not found from 0 to n-1 location, pos remains -1.