Switch statement not working....

Question

Hi All,

In writing an application I have come across a bug in a switch case statement, if I use an if else if it works translate that to a switch it does not, see below example.....

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
//why does the switch not work?

namespace SwitchTest
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click( object sender, EventArgs e)
{
int NtoDown = 0;
string strNtoDown = null ;
string NumRecordFiller = "" ;

strNtoDown = textBox1.Text;
NtoDown = Convert .ToInt16(strNtoDown);
// MessageBox.Show(NtoDown.ToString());
//NtoDown = 5;
MessageBox .Show(NtoDown.ToString());
/* switch(NtoDown)
{
case 0-9:
MessageBox.Show("Hi");
NumRecordFiller = "000";
break;

case 10-99:
NumRecordFiller = "00";
break;

case 100-999:
NumRecordFiller = "0";
break;

}*/
//MessageBox.Show("NumRecordFiller = " + NumRecordFiller.ToString() + "HELLO");
if (NtoDown <= 9)
NumRecordFiller = "000";
else if (NtoDown <= 99)
NumRecordFiller = "00" ;

else if (NtoDown <= 999)
NumRecordFiller = "0" ;

else if (NtoDown >= 999)
NumRecordFiller = "" ;

MessageBox .Show( "NumRecordFiller = " + NumRecordFiller.ToString());

}
}
}
This is odd as I think the switch is right or do I just live with the nested if else?

Glenn

Vulpes · Answer

You can't use ranges of values such as this in a C# switch statement: case 0 - 9: // code You can stack empty cases like this: case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8: case 9: // code but that would clearly be out of the question where you have more than a handful of cases and so you have to use an if/else if/else ladder instead. Incidentally, you can use ranges in the VB.NET Select statement which is one of the few features they have in that language which I envy.

Kunal Vaishya · Answer

thanks vulpes

Glenn Patton · Answer

It must have been a non Ansi compiler. That is the one area where VB (cough) seems to have one over C# also if it's not legal why does it compile with out warnings or error?

Vulpes · Answer

You definitely can't do it in standard C but, as you say, there may be some non-ANSI compilers around which allow it. It's not allowed in standard C++ or Java either.

Glenn Patton · Answer

You could do this in C (or was it due to a non-Ansi compiler?) Thanks alot. Glenn

Kunal Vaishya · Answer

Make sure NtoDown not null or blank or in Minus And dear tell me what you want exactly ?

Glenn Patton · Answer

The issue is NtoDown despite being in the switch statement!

Sandeep Singh Shekhawat · Answer

use case like: Switch(value) { case 0: case 1: case 2: . . . . . . . case 9: //do something break; } Thanks Sandeep

Glenn Patton · Answer

Hmmm, Thanks for that, I have not yet mangaged to generate enough files for that = to become apparent! Glenn

Kunal Vaishya · Answer

Dear this is very simple and you cant implement in switch case because you cant check the condition in case like this scenario

Switch statement not working....

Answers (10)