Checking for variable existance in C# as cfparam in CFM

Question

Can some tell me how you check to see if a variable has been defined in C#. Looking for ColdFusion function like cfparam. If the variable hasn't been define then define it else leave the variable unchanged.

wkb · Answer

You are. I basically gave myself this answer after I slammed out the above. Trying to switch gears between Coldfusion and asp.net sometimes takes a mental shift. Developing in Coldfusion is childs play by comparison. I sometimes wonder why the heck I'm banging my head against the wall trying to self teach myself such a complicated development environment as asp.net when Coldfusion is so darn easy... Thanks Wayne

spgilmore · Answer

Hmm. So you're wondering how to code the custom server control to know the path to the image right? If you have a path property on this control as you mentioned the page can tell the control where the image is right? That way the path is not explicitly defined in the control. Am I understanding you correctly?

wkb · Answer

The trouble I'm having for example is refering to an image directory from custom server controls. Let's say you have a control in a sub directory that is being consumed in a root directory or in another sub directory or even a different virtual directory completly and you don't want to explicitly define the path to the image in your controls. A practice in coldfusion is to set a variable in your parent page to this directory and to put this variable in the path of the control. Now you can find the image where ever you consume the control. Same applies for urls etc.

spgilmore · Answer

That is very poor programming practice. It leads to unmaintainable and bug-prone code. The proper way is to have descriptive variables so that each one has a single purpose or if you are uncertain you should declare the variable at the beginning of the scope so that it is always declared. The only time a variable should be declared conditionally is if it will only be used in a single context. If you have a situation where data not code determines the course of the program and you don't know what code will execute and what will happen to the variable you either need to refactor the code or reconsider your design or you may use special values in the variable to determine where it has been at any given point.

sunil · Answer

i hope you may need to declare the variable in your codebehind like the following. string tStr = null; Then while populating or later you can check whether it contain any value or is it still null. Please post if you derived any other way.