# strtok

###### tags: `EOS`

ex:
report | park |

第一次放 s 進入 strtok 切 "切割符號"
strtok(s , "|")
切割符號的字元會變成"\0"
用字元指標接： strtok 輸出到空字元前一格
`report ` report 後有空格

之後只要用0， strtok 會用之前的 buffer 繼續切
strtok(0 , "|")
` park ` park 前後都有空格

strtok(0 , "|") -> (null) 最後是空字元回傳 null

### NAME
strtok, strtok_r - extract tokens from strings
### SYNOPSIS

#include <string.h>

char *strtok(char *restrict str, const char *restrict delim);
char *strtok_r(char *restrict str, const char *restrict delim,
              char **restrict saveptr);

### DESCRIPTION
The strtok() function breaks a string into a sequence of zero or
more nonempty tokens. On the first call to strtok(), the string
to be parsed should be specified in str. In each subsequent call
that should parse the same string, str must be NULL.

The delim argument specifies a set of bytes that delimit the
tokens in the parsed string. The caller may specify different
strings in delim in successive calls that parse the same string.

Each call to strtok() returns a pointer to a null-terminated
string containing the next token. This string does not include
the delimiting byte. If no more tokens are found, strtok()
returns NULL.
...
### RETURN VALUE
The strtok() and strtok_r() functions return a pointer to the
next token, or NULL if there are no more tokens.

### ATTRIBUTES

| Interface | Attribute | Value |
| ---------- | ------------- | --------------------- |
| strtok() | Thread safety | MT-Unsafe race:strtok |
| strtok_r() | Thread safety | MT-Safe |

### EXAMPLE

#include <stdio.h>
#include <string.h> // strtok

int main() {
    char str[] = "Hello world, nice to meet you";
    const char* d = "  ,";
    char *p;
    p = strtok(str, d);
    
    while (p != NULL) {
        printf("%s\n", p);
        p = strtok(NULL, d);		   
    }
    return 0;
}