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std::strtok

From cppreference.com
< cpp‎ | string‎ | byte
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 multiples 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.

Contents

[edit] Parameters

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

[edit] Return value

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

[edit] 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.

[edit] Example

#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

[edit] See also

C documentation for strtok