C++ perform action when command line argument is empty [duplicate]

I've been working on a program recently, and got a bit stuck on a step. When the program is run from the shell, it performs an action when there are no parameters passed. Perhaps someone could assist me, or point me in a proper direction?

int main(int argc, char* argv[])
{
    string paramPassed = argv[1];
    if(paramPassed == "")
        cout << UseDriver();
    
    else if(paramPassed == memMap)
        cout << UseMemMap();
    
    else{
        if(paramPassed == help)
            cout << PrintProgramHelp();
        
        else if(paramPassed == helpMin)
            cout << PrintProgramHelp();
        
        else
            cout << "Wrong selection. Input --help or -h for more options." << endl;
    }
    cout << "Press any key to continue." << endl;   
    cin.get();
    return (0);
}

Above code on no input gives me:

terminate called after throwing an instance of 'std::logic_error'
what():  basic_string::_M_construct null not valid

What can I do? If I don't provide any parameter on program start, it gives me a segmentation fault.

Is there something I'm missing here?