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std::strtok(3)		      C++ Standard Libary		std::strtok(3)

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 suc-
       cessive tokens
	  from the same	string.

	    *  If  str is not a	null pointer, 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, it is the beginning of  the	token.
       The function then
	      searches from that point on for the first	character that is con-
       tained 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  charac-
       ter '\0'	and the
	      pointer  to  the following character is stored in	a static loca-
       tion for	subsequent
	      invocations.
	    * The function then	returns	the pointer to the  beginning  of  the
       token.
	    *  If  str	is a null pointer, the call is treated as a subsequent
       call to strtok:
	      the function continues from where	it left	 in  previous  invoca-
       tion. 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  de-
       limiters

Return value
	  Pointer to the beginning of the next token or	a nullptr 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
	  std::strtok.

	  Each call to this function modifies a	static variable: is not	thread
       safe.

	  Unlike  most	other tokenizers, the delimiters in std::strtok	can be
       different for
	  each subsequent token, and can even depend on	the  contents  of  the
       previous	tokens.

Possible implementation
	  char*	strtok(char* str, const	char* delim)
	  {
	      static char* buffer;

	      if (str != nullptr)
		  buffer = str;

	      buffer +=	std::strspn(buffer, delim);

	      if (*buffer == '\0')
		  return nullptr;

	      char* const tokenBegin = buffer;

	      buffer +=	std::strcspn(buffer, delim);

	      if (*buffer != '\0')
		  *buffer++ = '\0';

	      return tokenBegin;
	  }

	  Actual  C++ library implementations of this function delegate	to the
       C library, where
	  it may be implemented	directly (as in	MUSL libc), or in terms	of its
       reentrant
	  version (as in GNU libc).

Example
       // Run this code

	#include <cstring>
	#include <iomanip>
	#include <iostream>

	int main()
	{
	    char input[] = "one	+ two *	(three - four)!";
	    const char*	delimiters = "!	+- (*)";
	    char* token	= std::strtok(input, delimiters);
	    while (token)
	    {
		std::cout << std::quoted(token)	<< ' ';
		token =	std::strtok(nullptr, delimiters);
	    }

	    std::cout << "\nContents of	the input string now:\n\"";
	    for	(std::size_t n = 0; n <	sizeof input; ++n)
	    {
		if (const char c = input[n]; c != '\0')
		    std::cout << c;
		else
		    std::cout << "\\0";
	    }
	    std::cout << "\"\n";
	}

Output:
	"one" "two" "three" "four"
	Contents of the	input string now:
	"one\0+	two\0* (three\0- four\0!\0"

See also
			     finds the first location of any character from  a
       set of
	  strpbrk	     separators
			     (function)
			     returns the length	of the maximum initial segment
       that consists
	  strcspn	      of only the characters not found in another byte
       string
			     (function)
			     returns the length	of the maximum initial segment
       that consists
	  strspn	     of	only the  characters  found  in	 another  byte
       string
			     (function)
	  ranges::split_view a view over the subranges obtained	from splitting
       another view
	  views::split	     using a delimiter
	  (C++20)	     (class template) (range adaptor object)
	  C documentation for
	  strtok

http://cppreference.com		  2024.06.10			std::strtok(3)

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