Global scope variables can have unintended side effects.

Global scope variables can have unintended side effects.

• A. They are local to a function
• B. Can be called from other files
• C. They can have unintended side effects
• D. They are stored in a stack

Answer: (C)

Global scope variables are accessible from anywhere in the program, so any part of the code can read or modify them. This shared access means a change in one place can ripple through other parts of the program, producing unintended side effects that are hard to trace. That risk—unpredictable behavior caused by other parts of the code altering the same variable—is exactly what makes this concept important. For example, a global counter incremented by multiple modules or a global flag set by one component can cause other modules to behave differently without those modules expecting it. The key idea is the unexpected, cross-cutting impact of changes to globals. The other statements don’t capture this risk. Globals aren’t local to a function, since they exist outside function scopes. While globals can be accessed from other files in some environments, that visibility is not the primary concern here. And globals aren’t stored on the call stack; they reside in a fixed global area separate from the stack.

Global scope variables are accessible from anywhere in the program, so any part of the code can read or modify them. This shared access means a change in one place can ripple through other parts of the program, producing unintended side effects that are hard to trace. That risk—unpredictable behavior caused by other parts of the code altering the same variable—is exactly what makes this concept important.

For example, a global counter incremented by multiple modules or a global flag set by one component can cause other modules to behave differently without those modules expecting it. The key idea is the unexpected, cross-cutting impact of changes to globals.

The other statements don’t capture this risk. Globals aren’t local to a function, since they exist outside function scopes. While globals can be accessed from other files in some environments, that visibility is not the primary concern here. And globals aren’t stored on the call stack; they reside in a fixed global area separate from the stack.