[C语言]非递归实现strlen

#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
int strlen_(char *arr){
 assert(*arr != 0);//前置条件断言：代码执行之前必须具备的特性
 int num = 0;
 while (*arr){
  num++;
  arr++;
 }
 return num;
}
int main(){
 char *a = "abcdef";
 int ret = strlen_(a);
 printf("%d\n", ret);
 system("pause");
 return 0;
}