#include <iostream>
using namespace std;

int getX();
void logicBlock(int x);
void manipulateX(int* x);

int main(int argc, char **argv)
{
	int x = getX();
	logicBlock(x);
	// or: x = manipulateX(x);
	manipulateX(&x);
	logicBlock(x);
}

int getX()
{
	int x;
	cout << "Enter value: ";
	cin >> x;
	// did x really get read?
	return x;
}

void logicBlock(int x)
{
	switch(x) {
		case 4:
			cout << "It's 4" << endl;				

		break;
		case 5:
			cout << "It's 5" << endl;
		break;
		default:
			cout << "I don't know" << endl;
	}
}

void manipulateX(int* x)
{
	*x *= 2;
}

int manipulateX(int x)
{
	// or just: return x * 2;
	x *= 2;
	return x;
}