how to replace a string

#include <iostream>

void replace(char s[], char oldChar, char newChar) {
    for (int i = 0; s[i] != '\0'; i++) {
        if (s[i] == oldChar) {
            s[i] = newChar;
        }
    }
}

int main(int argc, char const *argv[]) {
    char s[] = "hello";
    replace(s, 'l', 'z');
    std::cout << s << std::endl;
    return 0;
}