Reverse a String In-Place

#include <stdio.h>

void reverse_string(char *str) {
    
    int len = 0;
    char swap = ' ';
    char c = ' ';

    // find the length
    while(c!='\0')
    {
        c = str[len];
        len++;
    }

    len = len-1;
    

    for(int i=0;i<len-1; i++)
    {
        for(int j=0;j<(len-1)-i;j++)
        {
            swap = str[j+1];
            str[j+1] = str[j];
            str[j] = swap;
        }
    }

}

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;
}