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Why must a variable be declared before it is used?
It’s best to declare variables when you first use them to ensure that they are always initialized to some valid value and that their intended use is always apparent. The alternative is typically to declare all variables in one location, typically at the top of the block or, even worse, at the top of a function.
Why must variables be declared?
“Why must I declare a variable?” You are required to announce your variables to the C compiler before you use them. That way, the compiler knows what the variables are called and what type of variables they are (what values they can contain). Officially, this process is known as declaring your variables.
When to declare variables close to their usage?
By declaring them close to their usage then you are implicitly stating this is where the variable is being use. Easier to see when that variable is used in the code. If you method is a few lines long then you can easily see where a variable is first used. It might help with identifying refactoring of code.
Where to place variable declarations in a function?
If you work in a codebase where the developers are against the idea of subroutines, then you’ll have 50 variable declarations at the start of the function and some of them might just be an “i” for a for-loop that’s at the very bottom of the function. I therefore developed declaration-at-the-top-PTSD from this and tried to do option 2) religiously.
When to declare local variables in a method?
The scope of local variables should always be as minimal as possible. So, I would declare the variable precisely there where it is used even if I have to re-declare it in multiple places within the same method. As a matter of fact, I would declare it precisely where it is used even if there was no if condition.
Do you have to declare variables in least scope?
People say as close to their usage as possible , They are not saying you should have to do that all the time,because they are some cases declaring variables in least scope will cause some overhead .The main reasons of that statement are Readability and giving variables the smallest scope you can .