std::strtok (3) - Linux Manuals

std::strtok: std::strtok

NAME

std::strtok - std::strtok

Synopsis

Defined in header <cstring>
char* strtok( char* str, const char* delim );

Finds the next token in a null-terminated byte string pointed to by str. The separator characters are identified by null-terminated byte string pointed to by delim.
This function is designed to be called multiple times to obtain successive tokens from the same string.

* If str != NULL, the call is treated as the first call to strtok for this particular string. The function searches for the first character which is not contained in delim.

      * If no such character was found, there are no tokens in str at all, and the function returns a null pointer.
      * If such character was found, is it the beginning of the token. The function then searches from that point on for the first character that is contained in delim.

            * If no such character was found, str has only one token, and the future calls to strtok will return a null pointer
            * If such character was found, it is replaced by the null character '\0' and the pointer to the following character is stored in a static location for subsequent invocations.

      * The function then returns the pointer to the beginning of the token

* If str == NULL, the call is treated as a subsequent calls to strtok: the function continues from where it left in previous invocation. The behavior is the same as if the previously stored pointer is passed as str.

Parameters

str - pointer to the null-terminated byte string to tokenize
delim - pointer to the null-terminated byte string identifying delimiters

Return value

Pointer to the beginning of the next token or NULL if there are no more tokens.

Notes

This function is destructive: it writes the '\0' characters in the elements of the string str. In particular, a string_literal cannot be used as the first argument of strtok.
Each call to this function modifies a static variable: is not thread safe.
Unlike most other tokenizers, the delimiters in strtok can be different for each subsequent token, and can even depend on the contents of the previous tokens.

Example

// Run this code

  #include <cstring>
  #include <iostream>

  int main()
  {
      char input[100] = "A bird came down the walk";
      char *token = std::strtok(input, " ");
      while (token != NULL) {
          std::cout << token << '\n';
          token = std::strtok(NULL, " ");
      }
  }

Output:

  A
  bird
  came
  down
  the
  walk