C++ error: no matching function for call to 'regex_match()'

Question

I'm struggling with this C++ compiler error to get my regex_match() function to work. The code:

#include <iostream>
#include <string>
#include <regex>
using namespace std;

struct Person {
    Person(string name, int age)
        : n{name}, a{age}
    {
        regex r("^([!:*&%#@^\\[\\]\"\'])+");             // :*[]"'&^%#@!
        for(char test : n) {
            cout << "Character: " << test;
            if(regex_match(test, r)) {
                cout << endl << "Error: wrong character!" << endl;
            }
        }
    }
    string n;
    int a;
};

int main() {
    Person Goofy("Goofy",11);
    return 0;
}

I want to check if n contains at least one of the characters I wrote in the regex r().

Btw, for people learning regex I've found the great website: https://regex101.com.

Any sugestions? Thx!!

krzaq · Accepted Answer · 2016-10-15 01:56:28Z

2

test is a character. There's no overload of std::regex_match for a character.

I'm not sure if you want to check every character against the list of characters or just the first one. If it's them all, you can use std::any_of:

char const constexpr m[] = R"(:*[]"'&^%#@!)";
for(char test : n) {
    if(any_of(begin(m), end(m), [test](char c){ return c == test; })) {
        cout << endl << "Error: wrong character!" << endl;
    }
}

Based on the additional comments I think I understand what you wanted: check if the string n contained any of the "illegal" characters. For this task std::regex_search is better suited:

regex r{R"([:*\[\]"'&^%#@!])"};

if(regex_search(n, r)){
    cout << endl << "Error: wrong character!" << endl;
}

edited Oct 15, 2016 at 1:56

answered Oct 15, 2016 at 0:40

krzaq

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5 Comments

phySical Over a year ago

I'm a newbie, can you explain please? Converting the char test to a string didn't work..

krzaq Over a year ago

I edited with an example. regex_match is supposed to match a string against a regex, not a single character. There's not much more than that to it.

krzaq Over a year ago

@m3n741 if you could tell me what exactly you're trying to achieve I could help you better, I hope.

Pete Becker Over a year ago

std::find_first_of(n.begin(), n.end(), m.begin(), m.end()) is equivalent to the test in your first snippet and doesn't need the loop or the lambda.

phySical Over a year ago

I wanted to check if the string n has any of the regex r signs in it and if I could use regex_match for that. Thank you for the quick answer :)

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