Stealth Fehler

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

int countIntInInteger(char* input){
    char* out;
    char* end = NULL;
    int value = strtol(input, &end, 10);
    out = malloc(value + strlen(input));  // could be shorter, but play it safe

    if(value == 0)
    {
        return value;
    }
    for (int i = 0; i != value; i++)
        {
            char c = end[i];
            if (c > 96 && c < 123) // ascii a-z
            {
                c -= 32;
            }
            out[i] = c;
        }
    free(out);
    return value;
}

int main() {
    char test[1024];
    scanf("%[^\n]%*c", test);
    countIntInInteger(test);
    return 0;
}