Programming-Function-Arguments

From DevRandom

Assumptions

1. Syntax is c/c++ like but this is not c or c++

2. Variable ctr has global scope

main()
{
	// define 2 element array & assign values
	int var[2];  
	var[0] = 1;
	var[1] = 1;

	// define a counter variable
	global int ctr;
	ctr=0;

	// print before calling any function
	cout << var[0];  	// this will print 1
	cout << var[1];  	// this will print 1

	/* Call function with arguments by name 
		& print		*/
	myfunc_value(var[ctr]);

	cout << var[0];  	// this will print 1
	cout << var[1];  	// this will print 1


	/* Call function with arguments by reference 
		& print		*/
	myfunc_ref(var[ctr]); 	//this results in a call to myfunc_ref(var[0])
	cout << var[0];  	// this will print 3
	cout << var[1];  	// this will print 1

	/* Call function with arguments by name 
		& print		*/
	myfunc_name(var[ctr]);	// var[ctr] is not evaluated at call time
	cout << var[0];  	// this will print 1
	cout << var[1];  	// this will print 3

	/* Call function with arguments by value result 
		& print		*/
	myfunc_value_result(var[ctr], var[ctr]);
	cout << var[0];  	// this will print 2
	cout << var[1];  	// this will print 1


	/* Function which accepts arguments by value */
	FUNCTION myfunc_value(int i, int j) {
		ctr = 1;
		i = i + 1; 
		j = j + 1; 
		// none of these changes will reflect in main
	}

	/* Function which accepts arguments by reference */
	FUNCTION myfunc_ref(int i, int j) {
		ctr = 1;
		i = i + 1;  
		j = j + 1; 
		// when i and j are changed the var[0] is changed 
	}

	FUNCTION myfunc_name(int i, int j) {
		ctr = 1;
		i = i + 1;  	// i is expanded as var[ctr] , i.e var[1]
		j = j + 1; 	// j is expanded as var[ctr] , i.e var[1]
		// so var[1] becomes 3
	}

	FUNCTION myfunc_value_result(int i, int j) 	{
		// at start var[0] is copied into i & j. So i = 1, j =1
		ctr = 1;
		i = i + 1;  	// i becomes 2
		j = j + 1; 	// j becomes 2
		// at the end the values are copied back to main
		// var[0] is copied with 2, then var[0] is copied again with 2
	}

}