How do I use std::string::find in C++11?

Can you explain how to use std::string::find in C++11?

Sure! The std::string::find function is used to locate a substring within a string. It returns the index of the first occurrence.

What does it return if the substring is not found?

If the substring is not found, it returns std::string::npos, which is a constant representing a non-position.

Can you give me a code example?

Of course! Here's a simple example:

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello, world!";
    size_t pos = str.find("world");
    if (pos != std::string::npos) {
        std::cout << "Found at index: " << pos << std::endl;
    } else {
        std::cout << "Not found" << std::endl;
    }
    return 0;
}