【C语言】三种方法实现strlen函数

#include <stdio.h>#include <assert.h>int my_strlen1(const char *str)//指针相减{assert(str);const char *ptr = str;while (*ptr++ != '\0'){;}return ptr - str - 1;}int my_strlen2(const char *str)//递归{assert(str);while (*str != '\0'){return 1 + (strlen(str + 1));}}int my_strlen3(const char *str)//计数器{assert(str);int count = 0;while (*str != '\0'){count++;str++;}return count;}int main(){char *str = "abcdefd";printf("%d\n", my_strlen1(str));printf("%d\n", my_strlen2(str));printf("%d\n", my_strlen3(str));system("pause");return 0;}