Pointer rewrite

[keyko18]

need help with pointer homework my return statement isnt working and i cant find in my textbook a good example on how to do it.

Problem is: the following function uses reference variables as parameters. rewrite the function so it uses pointers instead of reference variables and then demonstrate the function in a complete program

int doSomething(int &x, int &y)
{
int temp =x;
x = y *10;
y = temp * 10;
return x + y;
}


now my code is:

int doSomething(int *x, int *y)
{

int temp=*x;
*x= *y * 10;
*y = temp * 10;
return x+y;
}

int main()
{
int y,z;
cout << "Please enter a number" << endl;
cin >> y;
cout << "Please enter another number" << endl;
cin >> z;


doSomething(&y, &z);
system("Pause");
return 0;
}

[vlad from moscow]

Change the last statement of the function the following way

int doSomething(int *x, int *y)
{

int temp=*x;
*x= *y * 10;
*y = temp * 10;
return *x+*y;
}

[keyko18]

sweet it worked thank you

[vlad from moscow]

To demonstrate the function add the following statement to the main instead of the statement

doSomething(&y, &z);

std::cput << doSomething(&y, &z) << " = x(" << x << ") + y(" << y << ")'n";

or something similar

[chipp]

@vlad: how could that happened? i tested it, the code is:

#include <iostream>
using namespace std;

int doSomething(int *x, int *y)
{

int temp=*x;
*x= *y * 10;
*y = temp * 10;
return *x+*y;
}

int main()
{
int y,z;
cout << "Please enter a number" << endl;
cin >> y;
cout << "Please enter another number" << endl;
cin >> z;


doSomething(&y, &z);

cout << doSomething(&y, &z) << " = y(" << y << ") + z(" << z << ")'n" << endl;
system("Pause");
return 0;
}

result is:

Please enter a number
7
Please enter another number
3
1000 = y(30) + z(70)'n
Press any key to continue . . .

but, if i change the code:

#include <iostream>
using namespace std;

int doSomething(int *x, int *y)
{

int temp=*x;
*x= *y * 10;
*y = temp * 10;
return *x+*y;
}

int main()
{
int y,z;
cout << "Please enter a number" << endl;
cin >> y;
cout << "Please enter another number" << endl;
cin >> z;


doSomething(&y, &z);
doSomething(&y, &z);
cout << (y + z) << " = y(" << y << ") + z(" << z << ")'n" << endl;
system("Pause");
return 0;
}

result is:

Please enter a number
4
Please enter another number
9
1300 = y(400) + z(900)'n
Press any key to continue . . .

why?

[vlad from moscow]

First of all there is a typo in this statement

cout << (y + z) << " = y(" << y << ") + z(" << z << ")'n" << endl;

Shall be

cout << (y + z) << " = y(" << y << ") + z(" << z << ")\n" << endl;

or remove \n from the last string literal.

In the first case the order of evaluation of function arguments (arguments of operator << ) is undefined. So as arguments are usually evaluates from right to left x and y have values before calling doSomething the second time.