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.NET Forum / Languages / C# / September 2007Help With Variable Scope!
Hi everyone! Been a few weeks since i've asked a noob question :) At the moment I'm writing my First Form application compared to the few console bits and pieces that ive been working on. And due to me reading a few new books etc i've started cleaning up my code and sticking the engine part into its own class and methods to tidy it up. The thing i'm struggling with (due to my lack of understanding) is the scope of variables. I understand that the block of code which they are declared in are determines their scope etc but the trouble i'm having is carrying them accross to the main form etc. So for example: If I have the main form code with a click event say Form1.cs Which has something like: staticclass.Counter(); richtextbox1.Text = lineCount; Basically calling the counter function from the class and the coutner function counts the lines in a textfile etc where the variable lineCount is declared....how do I carry that back to the main form so that I can insert it into a textbox etc. Obviously at the moment its giving me a not decalred scope error....i'm guessing that It has to do with the arguments of the method in the class....but what do i need to do to persist the variable etc??? Sorry for the newb questions...im still learning :) Cheers steve Hi Steve, From your description i guess that you have the variable "lineCount" declared in the class "staticclass". In that case you have to specify the context of the variable also like given below: staticclass.Counter(); richtextbox1.Text = staticclass.lineCount.ToString(); but i think it will be a better option to make the Counter() method return the value directly, so that you can say "richtextbox1.Text=staticclass.Counter().ToString();" Cheers, Nimesh > Hi everyone! > [quoted text clipped - 30 lines] > Cheers > steve Yup, thats really what i'm trying to do is make the counter method return the variable....so how do i do that??? This is the code snippets to date: The calling statement from the main form: staticclass.Counter(); txttotal.Text = Convert.ToString.linecount; And now the class part: public class staticclass { public static int Counter() { int lineCount = 0; StreamReader sr = new StremaReader("url.txt"); String line; while ((line = sr.ReadLine()) != null) { lineCount++ } } So as you can see im trying to call the method from the main form and then checking how many lines of text etc and then trying to return it to a variable. I tried defining the exact object and method like you suggested but it still gave me the not in current context error etc. Any ideas? Steve > Hi Steve, > From your description i guess that you have the variable "lineCount" [quoted text clipped - 50 lines] >> Cheers >> steve oops.. i think you missed to put the "return" statement. see the lines i changed below. hope this helps. Cheers, Nimesh > Yup, thats really what i'm trying to do is make the counter method return > the variable....so how do i do that??? [quoted text clipped - 5 lines] > staticclass.Counter(); > txttotal.Text = Convert.ToString.linecount; //change this line to: txttotal.Text = staticclass.Counter().ToString(); > And now the class part: > [quoted text clipped - 10 lines] > lineCount++ > } //Add line here return lineCount; > } > [quoted text clipped - 61 lines] > >> Cheers > >> steve > Yup, thats really what i'm trying to do is make the counter method return > the variable....so how do i do that??? [quoted text clipped - 28 lines] > > Any ideas? You just need to end your Counter method with: return lineCount; That will return the value of the variable to the caller.  SignatureJon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If replying to the group, please do not mail me too Sorry guys, I missed typing that in when i chucked the code up here...I do have the return lineCount; statement in place...outside the while loop so that when its done it returns....but for some reason im still getting the doesnt exist in this context error. Steve >> Yup, thats really what i'm trying to do is make the counter method return >> the variable....so how do i do that??? [quoted text clipped - 35 lines] > > That will return the value of the variable to the caller. Steve, If you are using the ffollowing lines to get the value, It won't work! >>> staticclass.Counter(); >>> txttotal.Text = Convert.ToString.linecount; as you know, the staticclass.Counter(); function call returns the count. you have to either store it to a local variable and then assign it to the textbox or directly assign it to the text box. ie, either of the following blocks will work: int linecount = staticclass.Counter(); txttotal.Text = lineCount.ToString() or txttotal.Text =staticclass.Counter().ToString(); Cheers, Nimesh > Sorry guys, I missed typing that in when i chucked the code up here...I do > have the return lineCount; statement in place...outside the while loop so [quoted text clipped - 44 lines] >> >> That will return the value of the variable to the caller. > Yup, thats really what i'm trying to do is make the counter method return > the variable....so how do i do that??? [quoted text clipped - 30 lines] > > Steve The problem isn't that you can't reach the variable, the problem is that it doesn't exist any more. The variable is a local variable in the method, so it only exists while the method is running. When Nimesh suggested that you could reach the variable by specifying the class name, he assumed that the variable was a static variable in the class so that the variable actually did exist after the method ended. Just use return lineCount; as already has been suggested. SignatureGöran Andersson _____ http://www.guffa.com Yup that worked beautifully :) So I take it the returned value returns ONLY to the calling declaration??? how ould you handle it if the methor returns 2 or 3 variables???? Cheers Steve >> Yup, thats really what i'm trying to do is make the counter method return >> the variable....so how do i do that??? [quoted text clipped - 45 lines] > > as already has been suggested. One function can return only one value. You can use "ref" arguments to get more than value back from a function(but it is not same as return). Cheers, Nimesh > Yup that worked beautifully :) > [quoted text clipped - 54 lines] >> >> as already has been suggested. > Yup that worked beautifully :) > > So I take it the returned value returns ONLY to the calling declaration??? > how ould you handle it if the methor returns 2 or 3 variables???? Normally, it's best to make a method do one thing, and return a single result. If you really *have* to return multiple results, pass the parameters by reference using "ref" or "out". See http://pobox.com/~skeet/csharp/parameters.html for more details on this. SignatureJon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If replying to the group, please do not mail me too > Yup that worked beautifully :) > > So I take it the returned value returns ONLY to the calling > declaration??? Yes. > how ould you handle it if the methor returns 2 or 3 > variables???? There are several way. You can return an array, a list or a dictionary if the values are of the same type. You can put the values in a custom class or struct and return it. Or you can use the out or ref keywords to make output arguments. SignatureGöran Andersson _____ http://www.guffa.com Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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