The usage of ReverseFind to search for the last character in a string.

The ReverseFind function is used to search for the last occurrence of a specified character or substring in a string and return its position. Its usage is as follows:

int ReverseFind(const char* str, char c);
int ReverseFind(const char* str, const char* subStr);

In this case, str is the string to be searched, c is the character to be found, and subStr is the substring to be found.

Find the last occurrence of a character in a string.

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello world!";
    char c = 'o';
    int pos = str.rfind(c);  // 使用rfind函数查找字符
    if (pos != std::string::npos) {
        std::cout << "Character found at position: " << pos << std::endl;
    } else {
        std::cout << "Character not found." << std::endl;
    }
    return 0;
}

Result of running:

Character found at position: 7

Find the last occurrence of a substring in a string.

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello world!";
    std::string subStr = "world";
    int pos = str.rfind(subStr);  // 使用rfind函数查找子字符串
    if (pos != std::string::npos) {
        std::cout << "Substring found at position: " << pos << std::endl;
    } else {
        std::cout << "Substring not found." << std::endl;
    }
    return 0;
}

Output result:

Substring found at position: 6

It is important to note that if the specified character or substring cannot be found, the rfind function will return std::string::npos. You can determine whether the character or substring has been found by checking if the position is equal to npos.