Tutoring: demonstration of variable scope in C++;

scoping.cpp

#include <iostream>

using namespace std;

void someFunction();

int number = 0; // Scoped globally (everywhere inside this C++ program)



int main(){

	cout << number << endl; // Prints 0. Refers to global#number

	int number = 2; // Scoped to main()

	cout << number << endl; // Prints 2. Refers to main#number

	{ // Brackets create a new scoping level. Let's call this submain. 

		number = 4; // Modifies the next scope level up, main#number

		cout << number << endl; // Prints 4. Refers to main#number


		int number = 5; // Scoped to submain

		cout << number << endl; // Prints 5. Refers to submain#number

		int prime = 7; // Also scopped to submain

		cout <<  prime << endl; // Prints 7
	}

	cout << prime << endl; // When compiling, g++ will say "error: 'prime' was not declared in this scope"

	cout << number << endl; // Prints 4. Refers to main#number


	someFunction();

	/*
	
	(Without line 33, the program compiles and prints the following numbers in this order)

	0
	2
	4
	5
	7
	4
	0
	88

	 */


	return 0;
}


void someFunction(){

	cout << number << endl; // Prints 0. Refers to global#main

	int number = 88; // Scopped to someFunction();

	cout << number << endl; //Prints 88. Refers to someFunction#number


}