Question

Define a function CoordTransform() that transforms the function's first two input parameters xVal and yVal into two output parameters xValNew and yValNew. The function returns void. The transformation is new = (old + 1) * 2. Ex: If xVal = 3 and yVal = 4, then xValNew is 8 and yValNew is 10.
#include
using namespace std;
/* Your solution goes here */
int main() {
int xValNew;
int yValNew;
int xValUser;
int yValUser;
cin >> xValUser;
cin >> yValUser;
CoordTransform(xValUser, yValUser, xValNew, yValNew);
cout << "(" << xValUser << ", " << yValUser << ") becomes (" << xValNew << ", " << yValNew << ")" << endl;
return 0;
}

Answer 1

Answer:

Here is the function CoordTransform() that transforms the function's first two input parameters xVal and yVal into two output parameters xValNew and yValNew

void CoordTransform (int xVal ,int yVal ,int& xValNew, int& yValNew) { //function definition

xValNew = (xVal +1) *2; // adds 1 to old value (xVal) , multiplies the result by 2 and assigns that new value to xValNew

yValNew = (yVal +1) *2; } // adds 1 to old value (yVal) , multiplies the result by 2 and assigns that new value to yValNew

Explanation:

Here is the complete program:

#include <iostream> //to use input output functions

using namespace std; // to access objects like cin cout

void CoordTransform (int xVal ,int yVal ,int& xValNew, int& yValNew) { //function that takes four arguments

xValNew = (xVal +1) *2; // computes new value and assigns it to xValNew

yValNew = (yVal +1) *2;} // computes new value and assigns it to yValNew

int main() { // start of main function

//declares 4 int type variables xValNew, yValNew, xValUser, yValUser

int xValNew;

int yValNew;

int xValUser;

int yValUser;

cin >> xValUser; // takes value of xValUser from user

cin >> yValUser; // takes value of yValUser from user

CoordTransform(xValUser, yValUser, xValNew, yValNew); //function call

cout << "(" << xValUser << ", " << yValUser << ") becomes (" << xValNew << ", " << yValNew << ")" << endl; //prints the old and new values

return 0;}

In this program the function CoordTransform receives a reference to a variables  xValNew and yValNew so that it can modify the values of these variables. So  xValNew and  yValNew variables are declared as reference so they become an alternative name for the variables xValNew and  yValNew used in main() method . These variables are declared as reference in the function CoordTransform() by placing ‘&’ symbol in the declaration.

Suppose user enters 3 as value of xValUser and 4 as  value of yValUser

Now when the function  CoordTransform() is called it works as follows:

xValNew = (xVal +1) *2; this statement becomes:

xValNew = (3 + 1) * 2

xValNew = 4 * 2

xValNew = 8

Now this value is assigned to the xValNew of calling function (main) xValNew variable.

yValNew = (yVal +1) *2;

this statement becomes:

yValNew = (4 + 1) * 2

yValNew = 5 * 2

yValNew = 10

Now this value is assigned to the yValNew of calling function (main) yValNew variable.

So the output of the above program is:

(3, 4) becomes (8, 10)