Question

How to find all repeating characters in a string with C

Answer 1

#include <stdio.h>

#define SIZE 256

void count_occurrences(char s[], char occurrences[]) {
    int i = 0;
    while (s[i]) {
        occurrences[(int)s[i]]++;
        i++;
    }
}

int main() {
    char s[] = "java c c++ csharp php python";
    char occurrences[SIZE] = { 0 };

    count_occurrences(s, occurrences);

    int i = 0;
    while (s[i]) {
        if (occurrences[(int)s[i]] > 1) {
            printf("%c\n", s[i]);
            occurrences[(int)s[i]] = -1;
        }
        i++;
    }

    return 0;
}



/*
run:

a

c
+
h
p

*/

 

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