std::char_traits<CharT>::length

From cppreference.com
< cpp‎ | string‎ | char traits
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

#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