Declaring Variable

[daimous]

HI guys! is there any best practice in declaring variable in C#.net? Is it more efficient to declare all the variables that you will be using in your functions just outside it or in a place where when the application starts all the variable declared will be executed/initialized? Thanks in advance!

[RobDog888]

You declare them in the scope that they will be used in.

From widest to narrowset: You have app wide public variables, class/form level variables, procedural level vars and code block level.

You wouldnt have all vars as app wide public.

[daimous]

thanks a lot for that RobDog..But what if for example i have a function func and in that function i declare & Inialize several variables and that function wil be called several time s and so those variable will also be declare & Inialize several times..Isn't inefficient? Thanks in advance!

[jmcilhinney]

Declaring a local variable is about the smallest amount of work you can do. If a variable is used only in a single method and its value is not supposed to persist between calls then the variable should be declared locally. If it's value must be persisted then it must be declared at the class level.

[RobDog888]

Yes, it sounds like you have some procedural variables. So since the scope is only in the procedure its most efficient to initialize them within their scope. They dont retain their state between calls like John mentioned so there is no point in expanding their scope to persist outside the procedure.


Edit: 47,000 Posts!

[jmcilhinney]

Edit: 47,000 Posts!

I've already ordered a cake with 50,000 candles on it for you.

[daimous]

Thanks for that guys! It really helps..

[penagate]

Declare variables only when you can give them a meaningful value, and in the narrowest possible scope.

[wossname]

...Indeed.

Unless you are optimising a very tight loop in which case the normal rules don't always apply.