求字符串的长度 的其他方法

# include <stdio.h>   //递归方法int my_strlen(char *str){if (*str == '\0'){return 0;}elsereturn 1 + my_strlen(++str);}int main(void){char *a = "abscdfghjj";printf("%d\n", my_strlen(a));return 0;}

//指针相减int my_strlen(const char *str){const char *cur = str;   //利用一个变量记录字符串的首地址while (*str){str++;}return str - cur;}int main(void){char *a = "abscdfghjj";printf("%d\n", my_strlen(a));return 0;}