Copy a substring from const char* to std::string

Question

Would there be any copy function available that allows a substring to std::string?

Example -

const char *c = "This is a test string message";

I want to copy substring "test" to std::string.

Answer 1

You can use a std::string iterator constructor to initialize it with a substring of a C string e.g.:

const char *sourceString = "Hello world!";
std::string testString(sourceString + 1, sourceString + 4);

Answer 2

You might want to use a std::string_view (C++17 onwards) as an alternative to std::string:

#include <iostream>
#include <string_view>

int main()
{
    static const auto s{"This is a test string message"};
    std::string_view v{s + 10, 4};
    std::cout << v <<std::endl;
}