Property

Arezoo Sh

hi

Would any body like to help me to write the programme below?

in the class Test, there are 2 property (string s3, s4), string s3 just keep the numbers and string s4 just keep the letters.
forexmple in the main program:

if we assigned "asd3426ghf" to Test.s3:

   Test.s3="asd3426ghf";
   propert s3 only keeps, 3426, not asdghf

and

if we assigned "asd3426ghf" to Test.s4:

Test.s4="asd3426ghf";
   property s4 only keeps, asdghf, not 3426

how will it happen?
plz help me.

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes15y ago
Accepted answer
Well, properties don't actually keep anything - they're just methods under the hood. They need backing fields for storage.

Subject to that, the following should do what you want:

using System;
using System.Collections.Generic;

class Test
{
private string numbers, letters;

public string s3
{
get { return numbers; }
set { ExtractChars(value); }
}

public string s4
{
get { return letters; }
set { ExtractChars(value); }
}

private void ExtractChars(string value)
{
if (String.IsNullOrEmpty(value))
{
numbers = value;
letters = value;
return;
}

List numList = new List();
List letList = new List();

// ignore any characters which are neither digits or letters
foreach(char c in value)
{
if (Char.IsDigit(c))
numList.Add(c);
else if (Char.IsLetter(c))
letList.Add(c);
}

numbers = new string(numList.ToArray());
letters = new string(letList.ToArray());
}
}

class Program
{
static void Main()
{
Test t = new Test();
t.s3 = "asd3426ghf";
Console.WriteLine(t.s3);
Console.WriteLine(t.s4);
Console.WriteLine();

Test t2 = new Test();
t2.s4 = "asd3426ghf";
Console.WriteLine(t2.s4);
Console.WriteLine(t2.s3);
Console.ReadKey();
}
}
Vulpes15y ago
The problem is that strings are immutable - once you've created them they can't be changed.

So, statements like this give an error:

numbers[i] = c;

Also, you can't use char arrays because you don't know how long they need to be until you've analyzed 'value' into digits and letters, and once you've created an array you can't change its length.

So, this is why I used a List whose length is not fixed in advance.

As an alternative, you could use a StringBuilder which, unlike a string, is mutable and whose length is variable.
Arezoo Sh15y ago
Dear Vulpes

many Thanks for ur reply.
but I have some question about ur code, would u pls help me?

why u use the list? is it necessary?
can we use the string Numbers or letters instead of list?
for example:
            int i=0;
                 foreach(char c in value)
{
if (Char.IsDigit(c))
          {
             numbers[i]=c;
             i++;
           }
else if (Char.IsLetter(c))
          {
           letters[i]=c;
          i++;
           }
}
    why the code above is incorrect?
   can write this programme simpler than u write?
Vilas Gite15y ago
Hi Arezoo!

Please refer :

http://stackoverflow.com/questions/4804968/how-can-i-validate-console-input-as-integers

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