std::string c_str() method
- od C++20
- od C++11
- do C++11
// Const version only
constexpr const CharT* c_str() const noexcept;
// Const version only
const CharT* c_str() const noexcept;
// Const version only
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.
Writing to the character array accessed through c_str
is undefined behavior
Parameters
(none)
Return value
A pointer to the underlying character storage.
- od C++11
- do C++11
c_str()[i] == operator[](i)
for every i
in [ 0, size() ).c_str() + i == std::addressof(operator[](i))
for every i
in [ 0, size() ].Complexity
Constant - O(1).
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.
c_str()
and data()
perform the same function. (od C++11)
Example
#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());
}
}
c_func called with 'Emplary'
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