NAME¶

std::basic_string::operator[] - std::basic_string::operator[]

Synopsis¶

reference operator[]( size_type pos ); (until C++20)
constexpr reference operator[]( size_type pos ); (since C++20)
const_reference operator[]( size_type pos ) (1) (until C++20)
const; (2)
constexpr const_reference operator[]( size_type (since C++20)
pos ) const;

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() (until C++11)
(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'; // equivalent to s.back() = 'y';
std::cout << s << '\n';
}

Output:¶

rmx
Exemplar
Exemplary

See also¶

at accesses the specified character with bounds checking
(public member function)
front accesses the first character
(C++11) (public member function)
back accesses the last character
(C++11) (public member function)
operator[] accesses the specified character
(C++17) (public member function of std::basic_string_view<CharT,Traits>)