Shamsh Sameed Ahsan - 1 year ago 112
C Question

# Count number of repeating elements in an array in C

This program is for counting number of occurrences of each unique element.
Output is:

Program:

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

int main()
{
int *input;
int n,c;

printf("Enter the number of elements in the array:");
scanf("%d",&n);

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

printf("Enter %d elements \n",n);
for(c=0; c<n; c++)
scanf("%d",input+c);//POINTER NOTATION

if (sizeof(input) == 0) return 0;

int prev = input[0];
int count = 1;
int i;
int ARRAYSIZE = sizeof(input) / sizeof(int);

for (i = 1; i < ARRAYSIZE; i++)
{

if (input[i] == prev)
{
count++;
}
else
{
printf("%d=%d ", prev, count);
prev = input[i];
count = 1;
}

}

printf("%d=%d\n", prev, count);
free(input);
return 0;
}
``````

Enter the number of elements in the array:10

Enter 10 elements

1 1 1 1 1 2 2 3 3 6

1=1

Here I have entered 1 (5 times), 2 (2 times), 3 (2 times) and 6 (once)
But as you can see it only gives 1=1(1 times, but I've entered 1 five times.)
``````int ARRAYSIZE = sizeof(input) / sizeof(int);
Use `n` in place of `ARRAYSIZE`.
`sizeof(input)` returns the size of the pointer, `input`, not the size of the array. The `for` loop is not executed, the output is from the outer `printf`.