函数返回两个字符串的第一个公共字符

Question

is there is a function in the string library in c++ which takes 2 strings and return the first common characters between them? for example:

string x = "HelloWorld";
string y = "HelloFriends";

this function takes string x and string y and return string contains "Hello" which is the first common characters before difference. if there's not a function like this in the string library can i know how to implement a function like this?

Answer 1

The algorithm function you probably are looking for is std::mismatch :

#include <algorithm>
#include <string>
#include <iostream>

int main()
{
    std::string x = "HelloWorld"; 
    std::string y = "HelloFriends";
    auto pr = std::mismatch(x.begin(), x.end(), y.begin());
    std::string out(x.begin(), pr.first);
    std::cout << out;
}

Output:

Hello

Note that if you're using a compiler pre C++ 14, you need to check for the first range being shorter than the second range.

Better to read the linked page, since this function has added further overloads, depending on the version of C++ you're using.