help with function

[jamesfarrow]

I have what may seem like a trivial problem but it os something I can not get to work. How can I alter the match function to take an integer enabling different matches...
At the moment it is matching against the hardcoded number 3 in the function.
Any help is appreciated!

 #include <iostream>
#include <algorithm>
#include <vector>

//declare function to match strings
bool match(const std::string test){
    return test.size() == 3;
}

int main(int argc, const char * argv[]) {
    
    std::vector<std::string> texts;
    
    texts.push_back("one");
    texts.push_back("two");
    texts.push_back("three");
    texts.push_back("two");
    texts.push_back("four");
    texts.push_back("two");
    texts.push_back("three");

    std::cout << std::count_if(texts.begin(), texts.end(), match) << std::endl;
    
    return 0;
}

    

[Hengry]

You can add another parameter and use a for loop to check the vector instead of using count_if

[Ganado]

You can use a functor. A functor, in non-technical terms, is an object that acts like a function.

I modified this from
https://stackoverflow.com/questions/13525361/can-you-pass-an-additional-parameter-to-a-predicate
so please read that for more context

#include <iostream>
#include <algorithm>
#include <vector>

/*
//declare function to match strings
bool match(const std::string test){
    return test.size() == 3;
}
*/

struct match
{
    match(const size_t N) : n(N) {}
    const size_t n;
    bool operator()(const std::string& test)
    {
        return test.size() == n;
    }
};

int main(int argc, const char * argv[]) {
    
    std::vector<std::string> texts;
    
    texts.push_back("one");
    texts.push_back("two");
    texts.push_back("three");
    texts.push_back("two");
    texts.push_back("four");
    texts.push_back("two");
    texts.push_back("three");

    std::cout << std::count_if(texts.begin(), texts.end(), match(3)) << std::endl;
    
    return 0;
}

It certainly adds some boilerplate to the code, but it makes the end-user code look spotless.
You can also use lambdas to minimize boilerplate, as seen in the SO link.