C＃If（textbox.text = number）错误

Question

I making a quiz in which users would have to enter a number (eg 4) into a TextBox then the program would check if the number entered is correct. Unfortunately, I'm having some trouble with this part of the code.

So currently I have this code:

if(textbox1.Text=4)

but the 4 is underlined with the error message:

cannot implicitly convert type 'int' to 'string'.

Can I trouble you all to help me find out what's wrong with my code? Thank you so much!!

Answer 1

Since textbox1.Text is of type string , you have to parse :

   int answer;

   //  TryParse - the value entered can be treated as a valid integer 
   //  answer == correctAnswer - the answer provided is a correct one 
   if (int.TryParse(textbox1.Text, out answer) && answer == correctAnswer) {
     ...
   }

Please, notice that the implementation tolerates leading and traling spaces (typical problem in quizes): if user happens to input "4 " (trailing space) the answer will be accepted providing that correctAnswer == 4

Answer 2

if(textbox1.Text == Convert.ToString(4))

要么

if(textbox1.Text == "4")

Answer 3

You are trying to compare a string with an int .

You need to use if(textbox1.text == "4")

also note the double == for comparisons

Answer 4

您需要解析为int

if(Int32.Parse(textbox1.Text) == 4)

Answer 5

You are comparing a string (textbox1.Text) with an integer (4). To make this work you have to compare same data types. Some options:

if(textbox1.Text == "4") 

or

if(textbox1.Text == 4.ToString())

or

if(int.Parse(textbox1.Text) == 4)

NOTE: In the last option you can get an exception if the text in the textbox is not a number. So if you want to convert to integer than I would suggest:

int guessedNumber; 
Int32.TryParse(textbox1.Text, out guessedNumber);
if(guessedNumber == 4)

Answer 6

The Text property is of type string and 4 is an int so the comparison results in a compile time error.

Use the following code to perform the check.

if (int.Parse(textbox1.Text) == 4)
{
    // do something
}

If you're unsure whether the user is going to provide the input correctly or if you haven't set any validations on the model, then you should parse the input and then check whether the user entered 4. Here's the rextester link

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var input = "hello 4";
            // var input = "4";
            int number;
            var isNumber = int.TryParse(input, out number);
            if (isNumber)
            {
                if (number == 4)
                {
                    Console.WriteLine("The Number is 4");
                }
                else
                {
                    Console.WriteLine("The Number isn't 4");
                }
            }
            else
            {
                Console.WriteLine("Not a valid number");
            }
        }
    }
}

Answer 7

if(textbox1.Text == "4")
{
//Do Something
}

One way or another, you have to make sure both values are to make sure you are comparing two values "==" (not "=", unless u want to change the value) and that both values are same data type