如何正确编写（userInput> =“ 50”）？

Question

I mean to say "If the number typed by the user is greater than 50 then..." How can I write this properly? Because this error shows up in Visual Studio:

Operator '>=' cannot be applied to operands of type 'string' and 'string'

Console.Write("Enter a number: ");
        string userInput = Console.ReadLine();
        string message = (userInput >= "50") ? "Your number is greater than 50" : "You number is less than 50";

        Console.WriteLine(message);
        Console.ReadLine();

Answer 1

Strings are not numbers, so parse it:

int userInputNum = 0;
string userInput = Console.ReadLine();

if (int.TryParse(userInput, out userInputNum))
{
    string message = (userInputNum > 50) ? "Your number is greater than 50" : "You number is less than 50";
    Console.WriteLine(message);
}
else
{
    //Junk user input
}

Note that you can use int.Parse instead, but it will throw if the user inputs a non-number. The out keyword in the second argument forces the called function to populate the argument before returning (used because the signature of TryParse calls for it). Also, your logic was greater than or equal to 50. The code above is strictly greater than.

Your original code doesn't work because you are comparing the user input to a string (hence the "cannot be applied to operands of type 'string' and 'string' " ) because you have compared it to "50" . A string cannot be "greater than" or "less than" another string, only "equal to" ( == ) or "not equal to" ( != ).

More specifically, the > operator is not defined on string and so cannot be used to compare two of them.

Answer 2

change this

 string userInput = Console.ReadLine();

to

 var userInput = Convert.ToInt32(Console.ReadLine());

and (userInput >= "50") to

(userInput >= 50)

just remove qoutations

Answer 3

You've stored the value in a string variable. Thus, you should convert it to int so you are able to compare.

Console.Write("Enter a number: ");
    string userInput = Console.ReadLine();
    string message = (Convert.ToInt32(userInput) >= 50) ? "Your number is greater than 50" : "You number is less than 50";

    Console.WriteLine(message);
    Console.ReadLine();