Getting most frequent characters in array in c

Question

I am trying to get the most frequent characters from an array.

Here's my code

#include <stdio.h>

int main(void)
{
    int c[1000];
    char input[] = "abcdab";    
    int i;

    for(i=0; input[i]; i++)
    {
        c[input[i]]++; 
    }

    int j = 0;
    char str = 0;

    for(i=0; i<256; i++)
    {
        if(c[i] > j)
        {
            j = c[i];
            str = i;
        } 
    }

    printf("%c\n", str); 
    return 0;
}

It returns 'a'

But I want to get 'a' and 'b' since they are the most frequent characters in the array. Any help would be appreciated, thank you.

Answer 1

You are passing through the entire array looking for a maximum, and remembering the first one. With the solution you have, you need an additional loop:

for(i=0; i<256; i++){ // Look for all maximums
    if(c[i] == j) // If it is the maximum
    {
         printf("%c\n", i); // print the character
    } 
}

---

Note that your array c is not initialized to all zeroes, so it is purely by chance (not really) that the code is working. If you want c to be all zeroes, you need to declare it as int c[1000] = {0}; or to call memset on it.