---
name: "strsep"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/strsep"
---

# strsep(3)

string separate

## NAME

strsep - string separate

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <string.h>
```

**char \*strsep(char \*\*restrict** *stringp***, const char \*restrict** *delim***);**

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**strsep**():

```
    Since glibc 2.19:
        _DEFAULT_SOURCE
    glibc 2.19 and earlier:
        _BSD_SOURCE
```

## DESCRIPTION

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)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **strsep**() | Thread safety | MT-Safe |

## STANDARDS

BSD.

## HISTORY

4\.4BSD.

The **strsep**() function was introduced as a replacement for [**strtok**(3)](/strtok/3.md), since the latter cannot handle empty fields.

## CAVEATS

Be cautious when using this function. If you do use it, note that:

- •

  The identity of the delimiting character is lost.

## EXAMPLES

The program below is a port of the one found in [**strtok**(3)](/strtok/3.md), which, however, doesn't discard multiple delimiters or empty tokens:

```
$ ./a.out 'a/bbb///cc;xxx:yyy:' ':;' '/'
1: a/bbb///cc
         --> a
         --> bbb
         -->
         -->
         --> cc
2: xxx
         --> xxx
3: yyy
         --> yyy
4:
         -->
```

### Program source

```
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main(int argc, char *argv[])
{
    char *token, *subtoken;
    if (argc != 4) {
        fprintf(stderr, "Usage: %s string delim subdelim\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    for (unsigned int j = 1; (token = strsep(&argv[1], argv[2])); j++) {
        printf("%u: %s\n", j, token);
        while ((subtoken = strsep(&token, argv[3])))
            printf("\t --> %s\n", subtoken);
    }
    exit(EXIT_SUCCESS);
}
```

## SEE ALSO

[**string**(3)](/string/3.md)