Global Variables

Variables and constants can be declared outside of functions and procedures, within the program itself. Variables declared in this way are called global variables, which should be avoided. Global constants, on the other hand, are a great way of sharing consistent and meaningful values across your program.

Note

• Global variable is the term given to a variable that is declared within a program but outside any function or procedure.
• Global variables can be accessed by any instructions within a program.
• You should avoid using global variables. They can be accessed anywhere within a program, making it difficult to locate errors.
• Constants should be declared globally, and used to give meaning to values that are entered into your code.

Example

#include <string>
using std::string;

// Declare a global constant
const int INCREMENT_AMOUNT = 10;

// Declare (unnecessary) global variables
int x;
string message_text = "Hello world";

void my_procedure()
{
    // you can access x, message_text, and INCREMENT_AMOUNT here
}

int main()
{
    // you can access x, message_text, and INCREMENT_AMOUNT here
    return 0;
}