NAME
strsep - extract token from string
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <string.h>char *strsep(char **restrict \nstringp\n, const char *restrict \ndelim\n);strsep():
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Since glibc 2.19:
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_DEFAULT_SOURCE
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glibc 2.19 and earlier:
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_BSD_SOURCEDESCRIPTION
If *stringp is NULL, the strsep() function returns NULL and does nothing else. Otherwise, this function finds the first token in the string *stringp that is delimited by one of the bytes in the string delim. This token is terminated by overwriting the delimiter with a null byte ('\0'), and *stringp is updated to point past the token. In case no delimiter was found, the token is taken to be the entire string *stringp, and *stringp is made NULL.
RETURN VALUE
The strsep() function returns a pointer to the token, that is, it returns the original value of *stringp.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| strsep () | Thread safety | MT-Safe |
STANDARDS
None.
HISTORY
4.4BSD.
The strsep() function was introduced as a replacement for strtok(3), since the latter cannot handle empty fields. However, strtok(3) conforms to C89/C99 and hence is more portable.
BUGS
Be cautious when using this function. If you do use it, note that:
- •
This function modifies its first argument.
- •
This function cannot be used on constant strings.
- •
The identity of the delimiting character is lost.
EXAMPLES
The program below is a port of the one found in strtok(3), which, however, doesn't discard multiple delimiters or empty tokens:
$\n ./a.out 'a/bbb///cc;xxx:yyy:' ':;' '/'\n
1: a/bbb///cc
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--> a
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--> bbb
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-->
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-->
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--> cc
2: xxx
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--> xxx
3: yyy
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--> yyy
4:
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-->Program source
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main(int argc, char *argv[])
{
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char *token, *subtoken;
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if (argc != 4) {
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fprintf(stderr, "Usage: %s string delim subdelim\n", argv[0]);
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exit(EXIT_FAILURE);
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}
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for (unsigned int j = 1; (token = strsep(&argv[1], argv[2])); j++) {
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printf("%u: %s\n", j, token);
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while ((subtoken = strsep(&token, argv[3])))
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printf("\t --> %s\n", subtoken);
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}
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exit(EXIT_SUCCESS);
}SEE ALSO
memchr(3), strchr(3), string(3), strpbrk(3), strspn(3), strstr(3), strtok(3)