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

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

Strings library

Classes

basic_string

basic_string_view (C++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 (C++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 (C++17) Iterators basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) 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

Modifiers basic_string::clear basic_string::insert basic_string::insert_range (C++23) basic_string::erase basic_string::push_back basic_string::pop_back (DR*) basic_string::append basic_string::append_range (C++23) basic_string::operator+= basic_string::replace basic_string::replace_with_range (C++23) basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23)  basic_string::swap 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*) Operations basic_string::compare basic_string::starts_with (C++20) basic_string::ends_with (C++20) basic_string::contains (C++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) (C++20)(C++20) I/O operator<<operator>> getline Comparison operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) Numeric conversions stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11)  stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) Literals operator""s (C++14) Helper classes hash<std::basic_string> (C++11) Deduction guides(C++17)

 

const CharT* c_str()const;		(noexcept since C++11) (constexpr since C++20)

Returns a pointer to a null-terminated character array with data equivalent to those stored in the string.

The pointer is such that the range [c_str(), c_str()+ size()] is valid and the values in it correspond to the values stored in the string with an additional null character after the last position.

The pointer obtained from c_str() may be invalidated by:

• Passing a non-const reference to the string to any standard library function, or
• Calling non-const member functions on the string, excluding operator[], at(), front(), back(), begin(), rbegin(), end() and rend()(since C++11).

Writing to the character array accessed through c_str() is undefined behavior.

c_str() and data() perform the same function.

(since C++11)

Parameters

(none)

Return value

Pointer to the underlying character storage.

c_str()[i]== operator[](i) for every i in [​0​, size()).	(until C++11)
c_str()+ i ==std::addressof(operator[](i)) for every i in [​0​, size()].	(since C++11)

Complexity

Constant.

Notes

The pointer obtained from c_str() may only be treated as a pointer to a null-terminated character string if the string object does not contain other null characters.

Example

Run this code

#include <algorithm>#include <cassert>#include <cstring>#include <string>   extern"C"void c_func(constchar* c_str){ printf("c_func called with '%s'\n", c_str);}   int main(){std::stringconst s("Emplary");constchar* p = s.c_str();assert(s.size()==std::strlen(p));assert(std::equal(s.begin(), s.end(), p));assert(std::equal(p, p + s.size(), s.begin()));assert('\0'==*(p + s.size()));   c_func(s.c_str());}

Output:

c_func called with 'Emplary'

See also

front (DR*)	accesses the first character (public member function)
back (DR*)	accesses the last character (public member function)
data	returns a pointer to the first character of a string (public member function)