switch statemeent. Am I missing someting

TheFoZ

Hi Please accept my apologies if this sound silly but I cannot find a solution to this. I have a project I am converting to C# from VB. In VB I would do this.

Select Case Asc(UCase(Mid(strName, intPos, 1)))
Case 48 To 57
Let strNameSearch = strNameSearch & UCase(Mid(strName, intPos, 1))
Case 65 To 90, 193, 201, 205, 211, 218, 225, 233, 237, 243, 250
'some other code here
End Select

I have looked on the interweb and the only solution I have found is to use the switch statement like this

switch (statement that returns the ASCII value of the text)
{
case 48:
case 49:
case 50:
//and so on
}

This does seem a bit convoluted so is there an easy way like with the To statement in vb? (a link to some advanced switching will be greatly received) How do I get the ASC value of a character. Alot of people are saying to do Convert.ToInt32(....) but this brings me back errors as I am using a for loop to iterate through a substring. Your help is greatly appreciated.

The FoZ

Judah Gabriel Himango

Yes, there is no C# equivalent of VB's

Case 48 To 57

Best you can do inside a switch statement is case 48: case 49: case 50: etc. But that sounds really ugly. (In fact, the VB solution sounds like an ugly hackery.) A better option may be to utilize a table (such as a Dictionary<int, string>) to map integer keys to string values or functions that produce string values. Tell us what you want to do, and we'll tell you a good way to do it.

TheFoZ wrote:

Alot of people are saying to do Convert.ToInt32(....) but this brings me back errors as I am using a for loop to iterate through a substring.

char someChar = 'A';
int charValue = (int)someChar; // should be 65

Life, family, faith: Give me a visit. From my latest post: "A lot of Christians struggle, perhaps at a subconscious level, about the phrase "God of Israel". After all, Israel's God is the God of Judaism, is He not? And the God of Christianity is not the God of Judaism, right?" Judah Himango

TheFoZ

Thanks for the response. Do you have an example at all. What the function basically does is convert a string to an Upper Case string without any punctuation. e.g "This is a c# program!" converts to "THISISACPROGRAM" Many thanks

The FoZ

Judah Gabriel Himango

Way easier way to do that using the latest version of C#:

string input = "This is a c# program!";

var newChars = from character in input
where !char.IsPunctuation(character) && !char.IsWhiteSpace(character)
select char.ToUpper(character);

string result = new string(newChars.ToArray()); // results in "THISISACPROGRAM"

Life, family, faith: Give me a visit. From my latest post: "A lot of Christians struggle, perhaps at a subconscious level, about the phrase "God of Israel". After all, Israel's God is the God of Judaism, is He not? And the God of Christianity is not the God of Judaism, right?" Judah Himango

TheFoZ

Thanks for that. As you said, the code is for the latest version of C# and I am using 2005. I came up with this that seems to do the job

public static string CVNameSearch(string inputStr)
{
int x;
string returnStr;

    returnStr = "";

    for (x = 0; x<= inputStr.Length -1; ++x)
    {
        if (char.IsLetter(inputStr, x))
        {
            returnStr += inputStr.Substring(x, 1).ToUpper();
        }
    }

    return returnStr;

 }

Thanks for your help today

The FoZ

Guffa

Why not something simple, like this? str = Regex.Replace(str, "[^A-Za-z]+", string.Empty).ToUpper();

Despite everything, the person most likely to be fooling you next is yourself.

TheFoZ

Nice cheers. Don't suppose you could explain the syntax for me. I gather from the help that str is the input string, "[^A-Za-z]+" is the match but I'm not sure how it works. What is the string.Empty for? Thanks for your help

The FoZ

Ed Poore

[^A-Za-z]+ Basically this is a regular expression pattern which matches: [^]+ ==> any character that is not included inside the brackets A-Z ==> matches any character in the range A to Z a-z ==> matches any character in the range a to z So basically it replaces an non-alphabetic character with string.Empty. string.Empty (or String.Empty or System.String.Empty) are essentially the same as "" however when you reference them it does not create a new object but utilises one that's already been created, thus more memory efficient. A small difference but sometimes it matters.

Guffa

The pattern "[^A-Za-z]+" matches any non-letter characters, which then are replaced by an empty string, so that any non-letter characters are removed from the string. The ^ in the set makes it a negative set, mathing any characters except A-Z and a-z. If you want to keep any other characters, you just add them in the pattern, like for example "[^A-Za-zÅåÄäÖöÉéÈèËëÑñ]+".

Despite everything, the person most likely to be fooling you next is yourself.

Guffa

Ed.Poore wrote:

string.Empty (or String.Empty or System.String.Empty) are essentially the same as "" however when you reference them it does not create a new object but utilises one that's already been created, thus more memory efficient. A small difference but sometimes it matters.

The performance difference is really minimal, but there is another difference. If you always use string.Empty when you want an empty string, the code gets clearer. If you happen to stumble upon a "" in the code, you know that there is supposed to be something between the quotation marks, that perhaps got erased or left out by mistake. :)

Despite everything, the person most likely to be fooling you next is yourself.

PIEBALDconsult

Ed.Poore wrote:

does not create a new object but utilises one that's already been created

But in either case it stores an empty string in the executable at that point, because it's a constant, right? If so, there's no difference.

Mark Churchill

In C# you would use a bunch of if(c == foo) .... else if(30 < c && c < 100 && c == 10) ... etc. Of course with your particular issue doing it character by character probably isnt the best solution. I'd avoid using a Regex for something so simple. The framework has a bunch of stuff here thats probably useful (and culture invariant), eg: "foo bar".ToUpper().Replace(" ","") or similar. And who suggested LINQ? Just because LINQ is cool doesnt mean its appropriate to use it ;)

Mark Churchill Director Dunn & Churchill Free Download:
Diamond Binding: The simple, powerful, reliable, and effective data layer toolkit for Visual Studio.

Ed Poore

That's the best justification I've heard of it, thanks! I do use it but had always been slightly confused as to what the point was, now there's a valid reason.

Ed Poore

No it doesn't, I just compiled a sample and took a look at it under reflector and they definitely use two different methods, one compares a constant, the other compares the reference:

.entrypoint
.maxstack 2
.locals init (
[0] string toCompare,
[1] bool c1,
[2] bool c2)
L_0000: nop
L_0001: ldstr "Hello"
L_0006: stloc.0
L_0007: ldloc.0
L_0008: ldsfld string [mscorlib]System.String::Empty
L_000d: call bool [mscorlib]System.String::op_Equality(string, string)
L_0012: stloc.1
L_0013: ldloc.0
L_0014: ldstr ""
L_0019: call bool [mscorlib]System.String::op_Equality(string, string)
L_001e: stloc.2
L_001f: ret

TheFoZ

Thanks for the info. 'Every little helps' when it all comes down to it. The Regex expression does exactly what the old VB code does in about 10 lines and lots of iterations through a loop.

The FoZ

Ed Poore

It all depends on whether you understand (and like) regular expressions. Some people will do anything to avoid them.

I doubt it. If it isn't intuitive then we need to fix it. - Chris Maunder

Scott Dorman

Excellent reasons. Another benefit is that it ensures the comparisons are always performed the same way...no more some tests looking for length == 0 while others looking for "".

Scott Dorman

Microsoft® MVP - Visual C# | MCPD President - Tampa Bay IASA Hey, hey, hey. Don't be mean. We don't have to be mean because, remember, no matter where you go, there you are. - Buckaroo Banzai

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Scott Dorman

Another benefit is that it ensures the comparisons are always performed the same way...no more some tests looking for length == 0 while others looking for "".

Scott Dorman

Microsoft® MVP - Visual C# | MCPD President - Tampa Bay IASA Hey, hey, hey. Don't be mean. We don't have to be mean because, remember, no matter where you go, there you are. - Buckaroo Banzai

[Forum Guidelines][Articles][Blog]

Guffa

PIEBALDconsult wrote:

But in either case it stores an empty string in the executable at that point, because it's a constant, right? If so, there's no difference.

No, the string.Empty property returns a string that already exists in the mscorlib.dll. If you use "", that literal string will be added to your assembly. The difference is minimal, as it's only a few bytes of data, but there is a difference.

Despite everything, the person most likely to be fooling you next is yourself.