They make it more difficult to reason about your program since an apparently unrelated function call (or other piece of code) could change a global variable. This increase in coupling across various parts of your program also makes it harder to reuse parts that may otherwise be separate.Originally Posted by ulillillia
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Not to mention problems with name collisions, misspelling, reuse, etc.
I have a Windows API program I'm working on right now, it involves 12 files, passing the 10,000 lines of code mark and in that I have less than 20 globals and those are window handles, instance handles, and the programs settings struct. These pretty much have to be globalized so that code in other files can access the controls in the main window. Everything else is either local or passed into functions. (And fwiw... many programmers would class this as a "small" project.)
Last edited by CommonTater; 09-15-2011 at 11:56 AM.
Read this: Global Variables Are Bad
Unless you're using zero, this is probably not true.I'm using as few as I can.
Image data and arrays don't get special status.The bulk of the global variables is image data. These are in the form of arrays.
Good, so you got about 100 to 150 of the definitions correct.About 100 to 150 of the others are actual variables, nearly all of which initialized.
This is also known as the "I'm too lazy to pass them" argument. Declare them locally, pass them to functions as needed. Group related stuff in structs if need be, to keep it manageable. At the very least, create a singleton object with global data inside that, so access to it is well controlled.I use globals when multiple functions need to reference them.
Debugging is actually easier without globals, and conditional breakpoints work just as well, or better, when only using local variables.I sometimes use it for debugging, for conditional breakpoints.
I'd be curious what other such cases are good cause to break one of the oldest tenets of good programming practice.There are other such cases as well.
So you have 25% of your variables to move to local functions.I've got about 3 times more local variables than I do globals.
