Zhang Jiuan’ Notes

strtok的接口如下：

 char *strtok(char *s, const char *delim);

相关描述：
DESCRIPTION
       A ‘token’ is a nonempty string of characters not occurring in the string delim, followed by \0 or by a character occurring in delim.

       The  strtok()  function  can be used to parse the string s into tokens. The first call to strtok() should have s as its first argument. Subsequent calls should have the first
       argument set to NULL. Each call returns a pointer to the next token, or NULL when no more tokens are found.

       If a token ends with a delimiter, this delimiting character is overwritten with a \0 and a pointer to the next character is saved for the next call to strtok().   The  delim-
       iter string delim may be different for each call.

       The  strtok_r()  function  is  a  reentrant version of the strtok() function, which instead of using its own static buffer, requires a pointer to a user allocated char*. This
       pointer, the ptrptr parameter, must be the same while parsing the same string.

于是想着按如下方式使用：

#include <stdlib.h>
#include <string.h>

char names[100] = “abc|def|asc”;         
const char *tokens = “|”;

int main(int argc, char **argv)
{
   char *p_name = strtok(names, tokens);

    while (NULL != p_name) {
        printf(”%s\n”, p_name);
        p_name = strtok(g_app_names, tokens);
    }  

    return 0;
}

结果出错了，程序进入了死循环，什么原因呢？仔细看了一下接口描述，有这么一句：

 The first call to strtok() should have s as its first argument. Subsequent calls should have the first argument set to NULL. Each call returns a pointer to the next token, or NULL when no more tokens are found. 

原来只是第一次strtok转入原串，第二次之后，就使NULL就可以了，要不就进入死循环了。

#include <stdlib.h>
#include <string.h>

char names[100] = “abc|def|asc”;         
const char *tokens = “|”;

int main(int argc, char **argv)
{
   char *p_name = strtok(names, tokens);

    while (NULL != p_name) {
        printf(”%s\n”, p_name);

        p_name = strtok(NULL, tokens);
    }  

    return 0;
}

再运行一下吧：

abc

def

asc

正确了：）

多谢

张久安

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