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

< cpp‎ | string‎ | basic string

	(1)
CharT& front();			(until C++20)
constexpr CharT& front();			(since C++20)
		(2)
const CharT& front() const;				(until C++20)
constexpr const CharT& front() const;				(since C++20)

Returns reference to the first character in the string. The behavior is undefined if empty() is true.

Parameters

(none)

Return value

Reference to the first character, equivalent to operator[](0).

Complexity

Constant.

Notes

In libstdc++, front() is not available in C++98 mode.

Example

#include <iostream>
#include <string>
 
int main()
{
    std::string s("Exemplary");
    char& f1 = s.front();
    f1 = 'e';
    std::cout << s << '\n'; // "exemplary"
 
    std::string const c("Exemplary");
    char const& f2 = c.front();
    std::cout << &f2 << '\n'; // "Exemplary"
}

Output:

exemplary
Exemplary

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 534	C++98	std::basic_string did not have the member function `front()`	added

back (DR*)	accesses the last character (public member function)
front (C++17)	accesses the first character (public member function of `std::basic_string_view<CharT,Traits>`)