Thursday, 12 January 2012

Strtok Function

#include <stdio.h>
char *strtok(char *s, const char *delim) ;
A sequence of calls to this function split str into tokens, which are sequences of contiguous characters spearated by any of the characters that are part of delimiters.
On a first call, the function expects a C string as argument for str, whose first character is used as the starting location to scan for tokens. In subsequent calls, the function expects a null pointer and uses the position right after the end of last token as the new starting location for scanning.
To determine the beginning and the end of a token, the function first scans from the starting location for the first character not contained in separator (which becomes the beginning of the token). And then scans starting from this beginning of the token for the first character contained in separator, which becomes the end of the token.
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.
Return Value
A pointer to the last token found in string.
A null pointer is returned if there are no tokens left to retrieve.
#include <stdio.h>
int main ()
  char str[] ="- This, a sample string.";
  char * pch;
  printf ("Splitting string \"%s\" into tokens:\n",str);
  pch = strtok (str," ,.-");
  while (pch != NULL)
    printf ("%s\n",pch);
    pch = strtok (NULL, " ,.-");
  return 0;
It will proiduce following result:
Splitting string "- This, a sample string." into tokens:

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