How can I read user input from the console?

46

I want to get a number from the user, and then multiply that number with Pi. my attempt at this is below. But a contains gibberish. For example, if I insert 22, then a contains 50. What am I doing wrong? I don't get any compiler errors.

double a,b;
a = Console.Read();
b = a * Math.PI;
Console.WriteLine(b);

This question is tagged with c# .net console

~ Asked on 2011-09-02 07:51:01

The Best Answer is


67

I'm not sure what your problem is (since you haven't told us), but I'm guessing at

a = Console.Read();

This will only read one character from your Console.

You can change your program to this. To make it more robust, accept more than 1 char input, and validate that the input is actually a number:

double a, b;
Console.WriteLine("istenen sayiyi sonuna .00 koyarak yaz");
if (double.TryParse(Console.ReadLine(), out a)) {
  b = a * Math.PI;
  Console.WriteLine("Sonuç " + b); 
} else {
  //user gave an illegal input. Handle it here.
}

~ Answered on 2011-09-02 07:56:47


18

a = double.Parse(Console.ReadLine());

Beware that if the user enters something that cannot be parsed to a double, an exception will be thrown.

Edit:

To expand on my answer, the reason it's not working for you is that you are getting an input from the user in string format, and trying to put it directly into a double. You can't do that. You have to extract the double value from the string first.

If you'd like to perform some sort of error checking, simply do this:

if ( double.TryParse(Console.ReadLine(), out a) ) {
  Console.Writeline("Sonuç "+ a * Math.PI;); 
}
else {
  Console.WriteLine("Invalid number entered. Please enter number in format: #.#");
}

Thanks to Öyvind and abatischev for helping me refine my answer.

~ Answered on 2011-09-02 07:54:16


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