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

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. 2) If pos == size(), a reference to the character with value CharT() (the null character) is returned. (until C++11)

If pos == size(), a reference to the character with value CharT() (the null character) is returned.

For the first (non-const) version, the behavior is undefined if this character is modified to any value other than CharT() .

 (since C++11)

Parameters

pos - position of the character to return

Return value

Reference to the requested character.

Complexity

Constant.

Example

#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

See also

accesses the specified character with bounds checking
(public member function)

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/string/basic_string/operator_at