NAME

strsep — separate strings

SYNOPSIS

#include <string.h>

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

DESCRIPTION

The strsep() function locates, in the string referenced by *stringp, the first occurrence of any character in the string delim (or the terminating ‘\0’ character) and replaces it with a ‘\0’. The location of the next character after the delimiter character (or NULL, if the end of the string was reached) is stored in *stringp. The original value of *stringp is returned.

An “empty” field, i.e., one caused by two adjacent delimiter characters, can be detected by comparing the location referenced by the pointer returned by strsep() to ‘\0’.

If *stringp is initially NULL, strsep() returns NULL.

EXAMPLES

The following uses strsep() to parse a string, containing tokens delimited by whitespace, into an argument vector:

char **ap, *argv[10], *inputstring;

for (ap = argv; ap < &argv[9] &&
    (*ap = strsep(&inputstring, " \t")) != NULL;) {
	if (**ap != '\0')
		ap++;
}
*ap = NULL;

HISTORY

The strsep() function first appeared in 4.3BSD-Reno. It is intended as a replacement for the strtok(3) function. While the strtok(3) function should be preferred for portability reasons (it conforms to ANSI X3.159-1989 (“ANSI C89”)) it is unable to handle empty fields, i.e., detect fields delimited by two adjacent delimiter characters, or to be used for more than a single string at a time.