Reverse a String In-Place

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


int mystrlen( const char* str){
    const char *p = str;

    while(*p){
        p++;
    }

    return p-str;
}
void reverse_string(char *str) {
    
    int i = 0, e= strlen(str) -1;
    while(i<e){
        int temp = str[i];
        str[i++]=str[e];
        str[e--]= temp;
    }
}

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;
}