递归实现字符串翻转

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

char reserve_string(char *string)
{
    int len = strlen(string);
    if(len <= 1)
        return 0;
    else
    {


        char tmp = string[0];
        string[0] = string[len -1];
        string[len - 1] = '\0';
        reserve_string(string + 1);
        string[len - 1] = tmp;

    }

}
int main()
{
    char a[] = "evol";
    reserve_string(a);
    printf("%s\n",a );
    return 0;
}