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std::basic_string::c_str(3) C++ Standard Libary std::basic_string::c_str(3)

NAME

std::basic_string::c_str - std::basic_string::c_str

Synopsis


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 (since C++11)
[0, size()].

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(const char* c_str)
{
printf("c_func called with '%s'\n", c_str);
}


int main()
{
std::string const s("Emplary");
const char* 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 accesses the first character
(DR*) (public member function)
back accesses the last character
(DR*) (public member function)
data returns a pointer to the first character of a string
(public member function)

2024.06.10 http://cppreference.com