How to check if a character in a string equals "w"

I am failing to compare characters of a string in my program, I made a simpler version to showcase the problem:

#include <iostream>
using namespace std;


int main() {
        string s = "Hello world!";

        for(int i = 0; i<s.size(); i++) {
                if(s[i] == "w") {
                        cout << "This is a w!" << endl;
                }
        }
}

It returns this error:

so.cpp:10:25: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
10 | if(s[i] == "w")

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>Solution :

"w" is a pointer to the C string ['w', '\0'] in memory. You want to use single quotes instead so you are only comparing the character literal.

 if (s[i] == 'w') {
     cout << "This is a w!" << endl;
}