Question

How to remove odd frequency characters from a string in C

Answer 1

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

#define MAX_CHAR 256

void removeOddFrequencyChars(char *str) {
    int freq[MAX_CHAR] = {0};
    int len = strlen(str);

    // Count frequency of each character
    for (int i = 0; i < len; i++) {
        freq[(int)str[i]]++;
    }

    // Construct new string with only even frequency characters
    int index = 0;
    for (int i = 0; i < len; i++) {
        if (freq[(int)str[i]] % 2 == 0) {
            str[index++] = str[i];
        }
    }
    str[index] = '\0'; // Null-terminate the new string
}

int main() {
    char str[] = "c programming version 23";
    
    removeOddFrequencyChars(str);
    
    printf("%s\n", str);
    
    return 0;
}

 

/*
run:

ogmmingion

*/
 

 

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