std::basic_string::c_str

const CharT* c_str() const;

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)

Parameters

(none).

Return value

Pointer to the underlying character storage.

`data()[i] == operator[](i)` for every `i` in `[0, size())`.	(until C++11)
`data() + i == &operator[](i)` for every `i` in `[0, size()]`.	(since C++11)

Complexity

Constant.

Exceptions

(none)	(until C++11)
`noexcept` specification: `noexcept`	(since C++11)

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

#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()));
}

front (C++11)	accesses the first character (public member function)
back (C++11)	accesses the last character (public member function)
data	returns a pointer to the first character of a string (public member function)