Are global variables bad? [closed]

Answer 1

Global variables are as bad as you make them, no less.

If you are creating a fully encapsulated program, you can use globals. It's a "sin" to use globals, but programming sins are laregly philosophical.

If you check out L.in.oleum, you will see a language whose variables are solely global. It's unscalable because libraries all have no choice but to use globals.

That said, if you have choices, and can ignore programmer philosophy, globals aren't all that bad.

Neither are Gotos, if you use them right.

The big "bad" problem is that, if you use them wrong, people scream, the mars lander crashes, and the world blows up....or something like that.

Answer 2

Global variables are bad, if they allow you to manipulate aspects of a program that should be only modified locally. In OOP globals often conflict with the encapsulation-idea.

Answer 3

I'd answer this question with another question: Do you use singeltons/ Are singeltons bad?

Because (almost all) singelton usage is a glorified global variable.

Answer 4

Use of Global variables actually depends on the requirements. Its advantage is that,it reduces the overhead of passing the values repeatedly.

But your professor is right because it raises security issues so use of global variables should be avoided as much as possible. Global variables also create problems which are sometimes difficult to debug.

For example:-

Situations when the variables values is getting modified on runtime. At that moment its difficult to identify which part of code is modifying it and on what conditions.

Answer 5

Global are good when it comes to configuration . When we want our configuration/changes to have a global impact on entire project.

So we can change one configuration and the changes are directed to entire project . But I must warn you would have to be very smart to use globals .

Answer 6

Global variables are fine in small programs, but horrible if used the same way in large ones.

This means that you can easily get in the habit of using them while learning. This is what your professor is trying to protect you from.

When you are more experienced it will be easier to learn when they are okay.