Pros and Cons of Global Variables in C++

Global variables are variables that are defined outside of any function and can be accessed from anywhere in the program. They have both advantages and disadvantages.

Advantages:

1. They can be accessed from anywhere in the program, which can be convenient.
2. They can be used to share data between functions without having to pass the data as arguments.

Disadvantages:

1. They can make code harder to understand and maintain, because it's not clear which functions are modifying the global state.
2. They introduce the potential for naming collisions. If two parts of the program use the same global variable name, it can lead to bugs.
3. They make code less modular and harder to reuse, because functions that use global variables are tied to the global state.

In general, it's considered good practice to minimize the use of global variables. When you do use them, make sure to give them clear, descriptive names and document their purpose and usage.

Here's an example of a global variable:

1#include <iostream>
2
3int globalCounter = 0;
4
5void incrementCounter() { ++globalCounter; }
6
7int main() {
8  incrementCounter();
9  incrementCounter();
10
11  // Outputs 2
12  std::cout << globalCounter;
13}

12