93. Reverse a String In-Place

#include <stdio.h>

void reverse_string(char *str) {
    int len = 0;
    while(*(str + len) != '\0')len++; // To find the length of the string

for(int i = 0, j = len-1; i < j; i++, j--){
        // XOR swap without temp variable
        str[i] ^= str[j];
        str[j] ^= str[i];
        str[i] ^= str[j];
    }
}

int main() {
    char str[101];
    fgets(str, sizeof(str), stdin);

    // Remove newline
    int i = 0;
    while (str[i] != '\0') {
        if (str[i] == '\n') {
            str[i] = '\0';
            break;
        }
        i++;
    }

    reverse_string(str);
    printf("%s", str);
    return 0;
}