int ft_strlen(char *str)
{
    int len;
    len = 0;

    while (*str != '\0')
        len++;
    return (len);
}

char *ft_strrer(char *s)
{
    int i;
    int len;
    char temp;

    len = ft_strlen(s);  
    i = 0;
    while (i < len / 2)  
        {
            temp = s[i];
            s[i] = s[len -1 -i];
            s[len -1 -i] = temp;
            i++;       
        }
        return (s);
}

#include <stdio.h>

int main(void)
{
    char s[] = "Hello?";
    printf("avant ft : %s\n", s);
    ft_strrer(s);
    printf("apres ft : %s\n", s);
    return (0);
    
}