Expression must have integral or unscoped enum type.

[Mechennyy]

Hello everyone I am writing a small program for class that measures 3d distance.
I have been trying for figure out what I'm doing wrong for the last couple hours.
Here is my code;

#include <iostream>
#include <string>
#include <cmath>

using namespace std;

float dist3(float ux, float uy, float uz, float vx, float vy, float vz);

int main()
{
	cout << "The distance between (1, 2, 3) and (0, 0, 0) = " << dist3(0, 0, 0, 1, 2, 3) << endl;

	system("Pause");
}

float dist3(float ux, float uy, float uz, float vx, float vy, float vz)
{
	float answer = 0.0f;
	float distance = 0.0f;
	distance = (vx - ux) ^ 2 + (vy - uy) ^ 2 + (vz - uz) ^ 2;
	answer = sqrt(distance);

	return answer;
}

The error is at line 20.

Thanks

[MiiNiPaa]

(vx - ux) ^ 2

Why are you using bitewise xor on float?

[Mechennyy]

Why are you using bitewise xor on float?

No idea what that is.

[MiiNiPaa]

No idea what that is.

Then why are you using it?
That ^ it is bitwise xor operator
http://www.learncpp.com/cpp-tutorial/38-bitwise-operators/

[givememyusername]

you cant use ^ to do exponential need to use pow() function

[MiiNiPaa]

to do exponential need to use pow() function

For squares it is way faster to just multiply value by itself.

[Mechennyy]

Oh, alright Thanks, I was thinking ^ was like it was in regular math.

[MiiNiPaa]

Without being able to use ^ like that then I have no idea.

Let me quote wiki:
a square is the result of multiplying a number by itself. [..] Squaring is the same as raising to the power 2
( http://en.wikipedia.org/wiki/Square_%28algebra%29 )

^ doesn't mean what it does in math

It doesn't mean that in math too. It adopted to have that meaning in some programming languages and in some systems of writing math formulas in simple text editors or in typewriters
http://en.wikipedia.org/wiki/Exponentiation#In_programming_languages

Just use (vx - ux)*(vx - ux) etc. here.

[Mechennyy]

I'm currently not on my PC with VS but this is what I've come up with

#include <iostream>
#include <string>
#include <cmath>

using namespace std;

float dist3(float ux, float uy, float uz, float vx, float vy, float vz);

int main()
{
	cout << "The distance between (1, 2, 3) and (0, 0, 0) = " << dist3(0, 0, 0, 1, 2, 3) << endl;

	system("Pause");
}

float dist3(float ux, float uy, float uz, float vx, float vy, float vz)
{
	float answer = 0.0f;
	float distance = 0.0f;
	distance = (vx - ux) * (vx - ux) + (vy - uy) * (vy - uy) + (vz - uz) * (vz - uz);
	answer = sqrt(distance);

	return answer;
}

So I assume the program is now correct?

[MiiNiPaa]

Yes, it is correct. Some points:

1) It is good idea to initialize variable with correct value from the beginning:
float distance2 = (vx - ux)*//...
2) You can get rid of another variable by returning answer immediately:
return std::sqrt(distance2);
3) You can actually make it in 1 line, but it will impair readability too much, I think

[Mechennyy]

Alright Thanks, you keep answering my questions while i'm typing which is why I have asked things you just posted.

And by ^ in math I didn't mean like when you write it out on paper, I meant like if you type it in google or something.

[MiiNiPaa]

I meant like if you type it in google

Well, that is one of the systems used. It seems that the caret symbol had been started to use like that after advent of typewriters. Before that up arrow ↑ was often used in manuscrypts. I actually like it more. Sadly up arrow can easily be mistaken for Sheffer stroke now.

[Mechennyy]

Actually after thinking about it I'm not sure why I didn't just multiply it by itself from the start, that's how I did an exercise program yesterday. Must be because I had just looked up the formula for 3d distance and it showed the ^.