std::basic_string<CharT,Traits,Allocator>::operator[] (3) - Linux Manuals

std::basic_string<CharT,Traits,Allocator>::operator[]: std::basic_string<CharT,Traits,Allocator>::operator[]

NAME

std::basic_string<CharT,Traits,Allocator>::operator[] - std::basic_string<CharT,Traits,Allocator>::operator[]

Synopsis

reference operator[]( size_type pos ); (1)
const_reference operator[]( size_type pos ) const; (2)

Returns a reference to the character at specified location pos. No bounds checking is performed. If pos > size(), the behavior is undefined.

1) If pos == size(), the behavior is undefined. (until C++11)
2) If pos == size(), a reference to the character with value CharT() (the null character) is returned.
If pos == size(), a reference to the character with value CharT() (the null character) is returned. (since C++11)
For the first (non-const) version, the behavior is undefined if this character is modified to any value other than CharT() .

Parameters

pos - position of the character to return

Return value

Reference to the requested character.

Complexity

Constant.

Example

// Run this code

  #include <iostream>
  #include <string>

  int main()
  {
      std::string const e("Exemplar");
      for (unsigned i = e.length() - 1; i != 0; i /= 2)
          std::cout << e[i];
      std::cout << '\n';

      const char* c = &e[0];
      std::cout << c << '\n'; // print as a C string

      //Change the last character of s into a 'y'
      std::string s("Exemplar ");
      s[s.size()-1] = 'y';
      std::cout << s << '\n';
  }

Output:

  rmx
  Exemplar
  Exemplary