std::basic_string<CharT,Traits,Allocator>::at (3) - Linux Manuals

std::basic_string<CharT,Traits,Allocator>::at: std::basic_string<CharT,Traits,Allocator>::at

NAME

std::basic_string<CharT,Traits,Allocator>::at - std::basic_string<CharT,Traits,Allocator>::at

Synopsis


reference at( size_type pos );
const_reference at( size_type pos ) const;


Returns a reference to the character at specified location pos. Bounds checking is performed, exception of type std::out_of_range will be thrown on invalid access.

Parameters


pos - position of the character to return

Return value


Reference to the requested character.

Exceptions


Throws std::out_of_range if pos >= size().

Complexity


Constant.

Example


// Run this code


  #include <stdexcept>
  #include <iostream>
  #include <string>


  int main()
  {
      std::string s("message"); // for capacity


      s = "abc";
      s.at(2) = 'x'; // ok
      std::cout << s << '\n';


      std::cout << "string size = " << s.size() << '\n';
      std::cout << "string capacity = " << s.capacity() << '\n';


      try {
          // throw, even if capacity allowed to access element
          s.at(3) = 'x';
      }
      catch (std::out_of_range const& exc) {
          std::cout << exc.what() << '\n';
      }
  }

Output:


  abx
  string size = 3
  string capacity = 7
  basic_string::at

See also


           accesses the specified character
operator[] (public member function)

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