std::char_traits<CharT>::length

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

basic_string_view (C++17)

char_traits

 

std::char_traits

Member functions

char_traits::assign

char_traits::eqchar_traits::lt

char_traits::move

char_traits::copy

char_traits::compare

char_traits::length

char_traits::find

char_traits::to_char_type

char_traits::to_int_type

char_traits::eq_int_type

char_traits::eof

char_traits::not_eof

 

static std::size_t length( const char_type* s );		(until C++17)
static constexpr std::size_t length( const char_type* s );		(since C++17)

Returns the length of the character sequence pointed to by s, that is, the position of the terminating null character (CharT()).

Parameters

s

-

pointer to a character sequence to return length of

Return value

The length of character sequence pointed to by s.

Exceptions

(none)

Complexity

Linear.

Example

Run this code

#include <iostream>
 
void print(const char* str)
{
  std::cout << "string '" << str << "' ";
  std::cout << "length = " << std::char_traits<char>::length(str) << '\n';
}
 
int main()
{
  print("foo");
 
  std::string s("booo");
  print(s.c_str());
}

Output:

string 'foo' length = 3
string 'booo' length = 4