Evaluate a string with a switch in C++ [duplicate]

I want to evaluate a string with a switch but when I read the string entered by the user throws me the following error.

#include<iostream>
using namespace std;

    int main() {
        string a;
        cin>>a;
        switch (string(a)) {
        case "Option 1":
            cout<<"It pressed number 1"<<endl;
            break;
        case "Option 2":
            cout<<"It pressed number 2"<<endl;
            break;
        case "Option 3":
            cout<<"It pressed number 3"<<endl;
            break;
        default:
            cout<<"She put no choice"<<endl;
            break;
        }
        return 0;
    }

error: invalid cast from type ‘std::string {aka std::basic_string}’ to type ‘int