### C Program to Find Common Elements in Two Arrays

In this post, Let's write a c program to find common elements in two arrays.

Let’s assume we have following two sorted arrays p and q.

int p[] = {1,  3,  5,  7,  9};

int q[] = {1,  2,  3,  4,  5};

So the common elements in these two arrays are 1, 3, and 5.

# C Program to Find Common Elements in Two Arrays

Let's create a file named commoninarray.c and add the following source code to it.

``````#include<stdio.h>
#define max 100

int ifexists(int z[], int u, int v)
{
int i;
if (u==0) return 0;
for (i=0; i<=u;i++)
if (z[i]==v) return (1);
return (0);
}

void main()
{
int p[max], q[max], r[max];
int m,n;
int i,j,k;
k=0;
printf("Enter length of first array:");
scanf("%d",&m);
printf("Enter %d elements of first array\n",m);
for(i=0;i<m;i++ )
scanf("%d",&p[i]);
printf("\nEnter length of second array:");
scanf("%d",&n);
printf("Enter %d elements of second array\n",n);
for(i=0;i<n;i++ )
scanf("%d",&q[i]);
k=0;
for (i=0;i<m;i++)
{
for (j=0;j<n;j++)
{
if (p[i]==q[j])
{
if(!ifexists(r,k,p[i]))
{
r[k]=p[i];
k++;
}
}
}
}
if(k>0)
{
printf("\nThe common elements in the two array are:\n");

for(i = 0;i<k;i++)
printf("%d\n",r[i]);
}
else
printf("There are no common elements in two arrays\n");
}``````

To compile and run the above C program, you can use C Programs Compiler Online tool.

Output:

``````Enter length of first array:5
Enter 5 elements of first array
1
3
5
7
9

Enter length of second array:5
Enter 5 elements of second array
1
2
3
4
5

The common elements in the two array are:
1
3
5``````