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Manual Pages  — STRSEP


strsep – separate strings



Standard C Library (libc, -lc)


#include <string.h>

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


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., a character in the string delim occurs as the first character of *stringp) can be detected by comparing the location referenced by the returned pointer to ‘\0’.

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


The following uses strsep() to parse a string, and prints each token in separate line:
char *token, *string, *tofree;

tofree = string = strdup("abc,def,ghi"); assert(string != NULL);

while ((token = strsep(&string, ",")) != NULL)         printf("%s\n", token);


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

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

for (ap = argv; (*ap = strsep(&inputstring, " \t")) != NULL;)         if (**ap != '\0')                 if (++ap >= &argv[10])                         break;


memchr(3), strchr(3), strcspn(3), strpbrk(3), strrchr(3), strspn(3), strstr(3), strtok(3)


The strsep() function is intended as a replacement for the strtok() function. While the strtok() function should be preferred for portability reasons (it conforms to ISO/IEC 9899:1990 ("ISO C90")) 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. The strsep() function first appeared in BSD 4.4 .

STRSEP (3) December 5, 2008

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