What is use of c_str function In c++

Question

I have just started reading C++ and found c++ having rich functions for string manipulation which C does not have. I am reading these function and came across c_str()<

Answer 1

In C++, you define your strings as

std::string MyString;

instead of

char MyString[20];.

While writing C++ code, you encounter some C functions which require C string as parameter.
Like below:

void IAmACFunction(int abc, float bcd, const char * cstring);

Now there is a problem. You are working with C++ and you are using std::string string variables. But this C function is asking for a C string. How do you convert your std::string to a standard C string?

Like this:

std::string MyString;
// ...
MyString = "Hello world!";
// ...
IAmACFunction(5, 2.45f, MyString.c_str());

This is what c_str() is for.

Note that, for std::wstring strings, c_str() returns a const w_char *.