switch case range of values....

Glenn Patton

Hi All,

I'm trying to write a program that when it gets a piece of data back it will add a suitable padding to it to allow for processing. I have a rough bit of code using if then, if() loops that works. In the interest of this being maintainable later I am trying to use a switch() case the if() version is below: I need it to test over a range of values as while each case falling to the next works for a few values when it gets to 100's it is not really possible. How do you do this properly I have done this in C I know I have!
//works!!!!
if ((FileTotal < 9) || (FileTotal == 9))
FileIDFiller = "000";
if ((FileTotal < 99) && (FileTotal > 9))
FileIDFiller = "00";
if ((FileTotal < 999)&&(FileTotal >99))
FileIDFiller = "0";
if (FileTotal > 999)
FileIDFiller = "";

the switch() version I have tried is below also:

switch (Value)
{
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
case 8:
case 9:
MessageBox.Show("000");
break;
case 10:
case 99:
MessageBox.Show("00");
break;
case 100:
case 999:
MessageBox.Show("0");
break;
case 1000:
MessageBox.Show("");
break;
default:
MessageBox.Show("Something broke!!");
break;

}

There does not appear to be one!

12 Replies

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

Vulpes14y ago
Accepted answer
Yes, C# will allow you to 'stack' cases but it doesn't, unfortunately, allow you to use a range of values.

The same also applies to C and C++.

However, VB6 and VB.NET do allow you to use a range of values and it may be these languages which you were thinking about, Glenn.

Consequently, the only practical proposition when you're using C# is to code an if / else if / else ladder as you're already doing, though you can simplify it a bit to this:

if ((FileTotal <= 9)
FileIDFiller = "000";
else if ((FileTotal < 99))
FileIDFiller = "00";
else if ((FileTotal < 999)
FileIDFiller = "0";
else
FileIDFiller = "";
Glenn Patton14y ago
More reading of MSDN for me then!
Vulpes14y ago
No, it's just making use of one of the String class's constructors:

public String(char c, int count)

which generates a new string consisting of 'count' characters where each character is a 'c'.

So, here we're generating a string containing a number of '0' characters.
Glenn Patton14y ago
I think at 7 years old I was more interested in Chocolate Biscuits than PC's! I only started using that compiler when a bit of kit came back and didn't duck quick enough when the awful who can do this question was asked 'Who can do this?'. Indecently FilterID line you have there is it LINQ?
Vulpes14y ago
It sounds like you were a precocious child, Glenn ;)

Incidentally, you could replace your 'if' statements with this single line:

FileIDFilter = new String('0', Math.Max(4 - FileTotal.ToString().Length, 0));

It's probably a bit less performant than the 'if' statements but, what the heck, nowadays :)
Vulpes14y ago
It must be a non-ANSI standard compiler, as you say.

If it predates 1989, that's quite likely as C hadn't been standardized at the time even though the language went back to the early 1970's.
Glenn Patton14y ago
Thanks for that, I have found the C compiler that let you do that it is for an out date Micro (anything to with a Non-ANSI programming platform?) Cheers!
Glenn Patton14y ago
I am trying to use C# (VS2008) which won't let you!
Glenn Patton14y ago
Hmm, I think I need to explain what I am trying to do, using an integer that can be 1 to 1023 in size. I want to get a switch case going to relieve myself of the if() but how do you get a value to drop through (like 0 to 9) I can't seem to find a way of doing it easily...
Nattudurai Eswaramurthy14y ago
Even u can go with range of values like

case 0-4:
//Do Something
Break;
case 5:
//Do Something
Break;
case 6-100:
//Do Something
Break;

case 101-1000:
//Do Something
Break;

case 1001-10000:
//Do Something
Break;
Nattudurai Eswaramurthy14y ago
It works fine:
protected void Page_Load(object sender, EventArgs e)
{
Display(1000);
}

public void Display(int value)
{
string s = "Test";
switch (value)
{
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
case 8:
case 9:
//MessageBox.Show("000");
s = value.ToString();
break;
case 10:
case 99:
//MessageBox.Show("00");
s = value.ToString();
break;
case 100:
case 999:
// MessageBox.Show("0");
s = value.ToString();
break;
case 1000:
// MessageBox.Show("");
s = value.ToString();
break;
default:
// MessageBox.Show("Something broke!!");
s = value.ToString();
break;

}