Why does a const char* cast to std::string work?

Question

This cast puzzles me:

#include <string>
#include <iostream>
#include <memory>

using namespace std;

int main() {
    string str1 =  (string)"I cast this thing" +  " -- then add this";
    cout << str1 << endl;
}

Can someone explain why this c-style cast to string works (or is allowed)? I compared the generated optimized assembly with that from:

string str1 =  string("I construct this thing") +  " -- then add this";

and they appear to be identical, so I feel like I'm forgetting some c++ semantics that actually allow this kind of cast/construction to be interchanged.

 std::string str2 =  std::string("I construct this thing") +  " -- then add this";

Answer 1

A C-style cast will do a const cast and static cast or reinterpret cast whichever is possible.

A static cast will use a user-defined conversion if defined.

std::string has a constructor string(const char *).

The syntaxes std::string("something"), static_cast<std::string>("something") and (std::string)"something" are equivalent. They will all construct a temporary std::string using the std::string::string(const char *) constructor. The only difference between the syntaxes would be when casting pointers.