std::basic_string<CharT,Traits,Allocator>::c_str (3) - Linux Manuals

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


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


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

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().

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

c_str() and data() perform the same function. (since C++11)



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)




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.


// Run this code

  #include <algorithm>
  #include <cassert>
  #include <cstring>
  #include <string>

  int main()
    std::string const s("Emplary");
    assert(s.size() == std::strlen(s.c_str()));
    assert(std::equal(s.begin(), s.end(), s.c_str()));
    assert(std::equal(s.c_str(), s.c_str() + s.size(), s.begin()));
    assert(0 == *(s.c_str() + s.size()));

See also

front accesses the first character
        (public member function)

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