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

 

哋它亢++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (哋它亢++20)

Language support library

Concepts library (哋它亢++20)

Metaprogramming library (哋它亢++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (哋它亢++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (哋它亢++17)

Regular expressions library (哋它亢++11)

Concurrency support library (哋它亢++11)

Technical specifications

Symbols index

External libraries

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

basic_string_view (哋它亢++17)

char_traits

 

std::basic_string

Member functions basic_string::basic_string basic_string::~basic_string basic_string::operator= basic_string::assign basic_string::assign_range (哋它亢++23) basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (DR*) basic_string::back (DR*) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (哋它亢++17) Iterators basic_string::beginbasic_string::cbegin (哋它亢++11) basic_string::endbasic_string::cend (哋它亢++11) basic_string::rbeginbasic_string::crbegin (哋它亢++11) basic_string::rendbasic_string::crend (哋它亢++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (DR*) Modifiers basic_string::clear basic_string::insert basic_string::insert_range (哋它亢++23) basic_string::erase basic_string::push_back basic_string::pop_back (DR*) basic_string::append basic_string::append_range (哋它亢++23) basic_string::operator+= basic_string::replace basic_string::replace_with_range (哋它亢++23) basic_string::copy basic_string::resize basic_string::resize_and_overwrite (哋它亢++23)   basic_string::swap

Search basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Operations basic_string::compare basic_string::starts_with (哋它亢++20) basic_string::ends_with (哋它亢++20) basic_string::contains (哋它亢++23) basic_string::substr Constants basic_string::npos Non-member functions operator+ swap(std::basic_string) erase(std::basic_string)erase_if(std::basic_string) (哋它亢++20)(哋它亢++20) I/O operator<<operator>> getline Comparison operator==operator!=operator<operator>operator<=operator>=operator<=> (until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(哋它亢++20) Numeric conversions stoistolstoll (哋它亢++11)(哋它亢++11)(哋它亢++11) stoulstoull (哋它亢++11)(哋它亢++11) stofstodstold (哋它亢++11)(哋它亢++11)(哋它亢++11) to_string (哋它亢++11) to_wstring (哋它亢++11) Literals operator""s (哋它亢++14) Helper classes hash<std::basic_string> (哋它亢++11) Deduction guides (哋它亢++17)

 

CharT& front();	(1)	(constexpr since 哋它亢++20)
const CharT& front() const;	(2)	(constexpr since 哋它亢++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 libstd哋它亢++, front() is not available in 哋它亢++98 mode.

Example

Run this code

#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 哋它亢++ standards.

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

See also

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