#include <string.h>

char *strtok (
  char *str,          /* string to scan & delimit */
  const char *set);   /* set of delimeters */

A sequence of calls to strtok split str into tokens. A token is a character sequence separated by a single character delimiter that is part of the string set.

On the first call str is a non-NULL string pointer whose first character is used as the starting location to scan for tokens.

The strtok function begins searching the string str for the first delimiter character that is part of set. This end of the token is automatically replaced by a null-character by the function, and the beginning of the token is returned by the function. The end location is a saved pointer for subsequent calls.

In subsequent calls, when str is a NULL pointer, the strtok function searches from the saved pointer and uses therefore position right after the end of last token as the new starting location for scanning. The token delimiters pointed to by set may be different from call to call.

The strtok function returns a pointer to the first character of the next token from str. If there are no further tokens, a NULL pointer is returned.

Note that the contents of the string str are modified and broken into smaller strings (tokens).

#include <string.h>
#include <stdio.h> /* for printf */

void tst_strtok (void) {
  char *tok;

  tok = strtok ("This is a string of text", " \t\n");

  while (tok != NULL) {
    printf ("Token: %s\n", tok);
    tok = strtok (NULL, " \t\n");
  }
}