strlen的三种实现方式

#include <stdio.h>

#include <stdlib.h>

//实现strlen

int my_strlen1(char str[])//数组

{

int count = 0;

int i = 0;

while (str [i] != ‘\0‘)

{

count++;

i++;

}

return count;

}

int my_strlen2(char *str)//指针

{

int i = 0;

while (*str )

{

i++;

str++;

}

return i;

}

int my_strlen3(char *str)//递归

{

int i = 0;

if (*str == ‘\0‘)

{

return 1;

}

return 1 + my_strlen3(str + 1);

}

int main()

{

char str[] = "abcdef" ;

int ret = my_strlen1(str);

printf( "%s的长度为%d\n" , str, ret);

int ret2 = my_strlen2(str);

printf( "%s的长度为%d\n" , str, ret2);

int ret3 = my_strlen3(str);

printf( "%s的长度为%d\n" , str, ret3);

system( "pause");

return 0;