[C语言]递归实现strlen

#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
int strlen_(char *arr){
if (*arr != '\0'){
  return 1 + strlen_(arr + 1);
 }
 else
  return 0;
}
int main(){
 char *a = "abcdef";
 int ret = strlen_(a);
 printf("%d\n", ret);
 system("pause");
 return 0;
}