#include <iostream>
using namespace std;
 
int pureFunction(int number){
	return number + 1;	
}
 
int& notPureFunction(int& number){
	number = number + 1;
	return number;
}
 
int main() {
	int number = 1;
	cout << "number: " <<number << endl;
	cout << "---------------------------" << endl;
 
	cout << "pureFunction gives back: "<< pureFunction(number) << endl;
	cout << "number after pureFunction: " << number << endl;
	if( pureFunction(number) == pureFunction(number) ) {
		cout << "Two identical function call gives the same result. f(x) == f(x)" << endl;
		cout << "number after function equality test: " << number << endl;
	}
	cout << "---------------------------" << endl;
 
 
	cout << "notPureFunction gives back: "<< notPureFunction(number) << endl;
	cout << "number after notPureFunction: " << number << endl;
	if( notPureFunction(number) != notPureFunction(number) ) {
		cout << "Two identical function call does not give back the same result. f(x) != f(x)" << endl;
		cout << "number after function equality test: " << number << endl;
	}
	cout << "---------------------------" << endl;
 
	return 0;
}

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