Please help, C++ Swap function not working.

[mac071008]

Hey guys, I'm stuck on a homework program I'm supposed to type up.

Basically, the user should input a value that stores in the "first" variable. Then the user inputs a second value that is stored in the "second" variable. Then the program should call a swap function that will swap the first value and store it in the "second" variable, and vice versa.
(The formal parameters are supposed to be named number1 and number2 as I included).

Here is my program:
---------------------------------------

#include "stdafx.h"
#include <iostream>
using namespace std;



void swap(float, float);

int main()
{
float first;
float second;

cout << "Enter the first number then hit enter." << endl;
cin >> first;

cout << "Enter the second number then hit enter." << endl;
cin >> second;

cout << endl;

cout << "You input the numbers as " << first << " and " << second << "." << endl;
swap(first, second);
cout << "After swapping, the first number has the value of " << first << " which was the value of the second number." << endl;
cout << "The second number has the value of " << second << " which was the value of the first number." << endl;


system("pause");
return 0;
}

void swap(float number1, float number2)
{
float x = number1;
number1 = number2;
number2 = x;
}


Thank you in advance.

[mac071008]

I don't mean to double post, but I actually just corrected the problem with pointers. My new question is, is there an alternate way of doing this in the swap function?

[firedraco]

Yes, but it only works with integral types:

number1 ^= number2;
number2 ^= number1;
number1 ^= number2;

However, it's usually slower than just using a temporary, since the compiler can optimize that function for you, but usually has a harder time optimization the random xors.

[mac071008]

Oh I gotcha, what do you mean by 'integral types'? I apologize, I'm not too advanced in C++ and I enjoy learning more.

[Zhuge]

Integral being the adjectival form of "integer". So ints, chars, etc.
You could also use references to accomplish the swap, like the std::swap() function does.

[ascii]

bitwise operators are more efficient so you might want to use them in your code :)
also theres generally no advantage to using floats, so i would just use doubles for more precision :)

[Disch]

bitwise operators are more efficient so you might want to use them in your code :)

Not really.

theres generally no advantage to using floats, so i would just use doubles for more precision

Floats use less memory. Although if precision is important, then yeah doubles would be the way to go.