C# how to implement a function in this code?

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I have to implement a function which can receive a string parameter and return a bool type variable. Then the function must verify if the said sent parameter is integer and return true if it is or false if it isn't. Can you please help? i am new to C# and trying to learn on my own. Thank you.

What I have tried:

C#

class Program
    {

        static void Main(string[] args)
        {
            string[] values = { "10x", "10", "100xx" };
            foreach (var value in values)
            {
                int g;
                if (int.TryParse(value, out g))
                    Console.WriteLine("Value '{0}' is a number.", value, g);
                else
                    Console.WriteLine("Value '{0}' is not a number.", value == null ? "<null>" : value);
            }
            
        }
    }

Posted 24-Nov-16 21:22pm

Member 12869977

Updated 24-Nov-16 23:36pm

Richard MacCutchan

v9

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Comments

Philippe Mori 25-Nov-16 10:18am

In Visual Studio, you can select some code and right-click and there will be an option to generate a function.

Otherwise, you are better to read some books or tutorial and try thing as you learn them...

Philippe Mori 25-Nov-16 16:59pm

Is it an assignment or something you want to do by yourself. If it is an assignment, then checkString from solution 2 would be what you ask.

And if it is your own code, then in that case, it does not make sense to replace int.TryParse by something else as it already does exactly what you need.

Member 12869977 27-Nov-16 13:51pm

It's sort of an assignment. I am doing a sheet of exercises from a book I've been studying and that what the exercise asked me to do .. I know my code works without the function but I need it because it said to create a function who will be called from Main and the second part of the exercise is saying to modify the function to receive a another string parameter in which I will the send the type of parameter I wish to validate: number or data. The function must be modified in such way to take account of this new parameter. If the parameter is a number we will display it's a number, if it's a data we will say it's a data... so that's the reason .. sorry for the bad English it's my second language .. still haven't figured out the second part so if you have any ideas feel free to give me some .. and thank you

3 solutions

Solution 1

C#

A simplifield way like this should do. 

(you should test it if a string containing a real/float/double stringified value is passed in such as "3.14159" etc... (you could use the string contains method and check for decimal being present in the string (except the last position on the right).


static bool IsThisAnInteger( string input = "" ){
  int g = 0;
  try {
    Int.Parse(input,out g);   // the Parse method will throw an error if not int.
    return true;
  } catch( Exception x){
    ;  // you'll end up here if input is not a stringified int.
  }
  return false;
}

Posted 24-Nov-16 21:47pm

23741

Comments

F-ES Sitecore 25-Nov-16 4:18am

Never use exceptions for this, exceptions are very expensive which is why the TryParse method exists. Only use Parse if you know the input is of the correct format and won't throw an exception, otherwise use TryParse.

Philippe Mori 25-Nov-16 10:20am

By the way, what OP does is already better that what you propose to do...

[no name] 25-Nov-16 16:15pm

Can you expand on that?

Philippe Mori 25-Nov-16 16:25pm

Calling int.TryParse is preferable over your IsThisAnInteger function as it will do the validation, the value is ready for use, the code is shorter, it require to pass a string and it use framework code.

[no name] 25-Nov-16 16:46pm

Please read the first sentence in the posters question.

It is imperative that one understand the question prior to providing an answer.

Please provide your solution to the poster's original question as this would be indicative of you being part of the solution as the poster would gain from your input.

As they say, you're either part of the solution, or you are part of the problem.

I look forward to your solution as asked by the poster in the first place.

Philippe Mori 25-Nov-16 16:56pm

Well, then OP idea is wrong if he wants to do that by himself... and if it is an assignment, then Solution 2 checkString function is much better than yours.

So maybe I misread OP question but obviously from its code, it would make no sense at all to write such function...

Philippe Mori 25-Nov-16 17:01pm

Given than OP said that he is learning by his own, I don't think we help him by giving him exactly what he asks... but instead we should suggest him the best way to do it which is already what he has done.

Solution 4

I believe TryParse does a try/catch internally.

Posted 24-Nov-16 23:14pm

23741

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Sossi.Mond · Accepted Answer · 2016-11-24T22:53:00

An example of how you could do it with
" tryParse ".
The code could be even smaller by removing the method
" checkString(string str) "
and replacing it in the if statement with
a TryParse.

C#

static void Main(string[] args)
{
	string[] strArray = {"100k", "10", "10k" };
	string strPlaceholder;

	Console.WriteLine("\n ~~ Press F12 to quit ~~\n");

	do
	{
		foreach (string str in strArray)
		{
			strPlaceholder = null;

			if (!checkString(str))
			    strPlaceholder = "not";

			Console.WriteLine($"# {str} is {strPlaceholder} a valid Number");
		}

	} while (Console.ReadKey(true).Key != ConsoleKey.F12);
			
}

static bool checkString(string str)
{
	int placeholder;

	return int.TryParse(str, out placeholder);
}