std::string rfind

std::string rfind is a member function of the std::string class in C++. It is used to find the last occurrence of a substring within a given string.

Here is an example usage of the rfind function:

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello, World! This is C++.";

    // Find the last occurrence of "is" in the string
    size_t pos = str.rfind("is");

    if (pos != std::string::npos) {
        std::cout << "Last occurrence found at position: " << pos << std::endl;
    } else {
        std::cout << "Substring not found." << std::endl;
    }

    return 0;
}

In this example, the rfind function is used to find the last occurrence of the substring "is" in the string "Hello, World! This is C++.". If the substring is found, the function returns the position of its first character; otherwise, it returns std::string::npos (a special value indicating "not found").