How to make a Mandelbrot Set?

[Hak]

[QUOTE=nullsquared;20713857][cpp]
/*no const, return values are inherently const*/A A::operator* (const A &param) // use a const-ref here to avoid copies
{
// first way
(*this) + param;

// second way (explicit call)
operator+(param);
}
[/cpp][/QUOTE]

OH! So [i]this[/i] is just a pointer! Derp.

Thanks again, mate.

[Hak]

Me again. Anyways, I'm translating my old Mandel code from Java into C++. However, ran into a strange little bug I can't figure out. Obviously, it's going to be something obvious and facepalming-worthy but nevertheless:

[cpp]
class Mandelbrot : public Fractal {
ComplexNumber z, seed;
ushort iterationsUsed;
double bounds[];
static const ushort ITERATIONS = 256;
public:
Mandelbrot(ushort width, ushort height) {
bounds = {-2.25, 0.75, -1.5, 1.5};
};
};
[/cpp]

Gives me errors, whereas:

[cpp]
class Mandelbrot : public Fractal {
ComplexNumber z, seed;
ushort iterationsUsed;
static const ushort ITERATIONS = 256;
public:
Mandelbrot(ushort width, ushort height) {
double bounds[] = {-2.25, 0.75, -1.5, 1.5};
initFract(width, height, bounds);
};
};
[/cpp]

Compiles fine, but I want bounds to be visible to the entire class, not just its' constructor. It also works if I throw it as an instance field to the entire file.

Thoughts? (inb4 obvious problem)

[MakeR]

-snip-

[nullsquared]

You can't assign arrays like that. You can only initialize them like that.

[Hak]

[QUOTE=nullsquared;20722373]You can't assign arrays like that. You can only initialize them like that.[/QUOTE]

So then would this work?

[cpp]
class Mandelbrot : public Fractal {
ComplexNumber z, seed;
ushort iterationsUsed;
double bounds[] = {-2.25, 0.75, -1.5, 1.5};
static const ushort ITERATIONS = 256;
public:
Mandelbrot(ushort width, ushort height) {
};
};
[/cpp]

I thought this didn't work either when I tried it... hrm.

[nullsquared]

No, that only works for constant statics.

You can, however, do this:

Mandelbrot(ushort width, ushort height)
{
    double arr = { /* whatever */ };
    std::copy(arr, arr + 4, bounds); // copy arr into bounds
} /* no ; here btw */

[Hak]

I've noticed that most of the tutorials I've looked through declare most of their class methods outside of the class that they belong to (i.e. all non-single-line methods). Is there any specific reason for doing so, or is it merely preference?

Also, thanks again Null.

[nullsquared]

[QUOTE=Hak;20750191]I've noticed that most of the tutorials I've looked through declare most of their class methods outside of the class that they belong to (i.e. all non-single-line methods). Is there any specific reason for doing so, or is it merely preference?[/QUOTE]

You mean outside of the header file?

That's very useful to keep compilation times to a minimum and reduce code size. Otherwise, every time you include that header file, *all* the code for the class is also included and compiled. If you keep definition (source) separate from declaration (header), most of the code is only compiled once.

[Hak]

[QUOTE=nullsquared;20750281]You mean outside of the header file?

That's very useful to keep compilation times to a minimum and reduce code size. Otherwise, every time you include that header file, *all* the code for the class is also included and compiled. If you keep definition (source) separate from declaration (header), most of the code is only compiled once.[/QUOTE]

I meant stuff like:

[cpp]
class CVector {
public:
int x,y;
CVector () {};
CVector (int,int);
CVector operator + (CVector);
};

CVector::CVector (int a, int b) {
x = a;
y = b;
}
[/cpp]

Where the constructor is defined outside the class. Unless that's what you meant.

[ShaunOfTheLive]

Yeah, the first part should be in your .h and the second part should be in your .cpp. It keeps things organized. Header is just declaring things; .cpp is actually defining it. You may need to include your header in multiple files so that other .cpp files know about its structure.

[Hak]

[QUOTE=shill le 2nd;20750440]Yeah, the first part should be in your .h and the second part should be in your .cpp. It keeps things organized. Header is just declaring things; .cpp is actually defining it. You may need to include your header in multiple files so that other .cpp files know about its structure.[/QUOTE]

OH I see, that makes sense. Up until now I've just used my header for defines, typedefs, and includes :S

[lemming77]

[QUOTE=Hak;20751007]OH I see, that makes sense. Up until now I've just used my header for defines, typedefs, and includes :S[/QUOTE]

I'd say typedefs and includes should go in the header files, since then they can be used from everywhere else. But definitions I'd advise you to seperate into source files.

[editline]03:42AM[/editline]

Oh wait, by defines, you mean #define preprocessor statements right? Yeah, I'd put them in headers too, just so they're declared before they're used.

[gparent]

[QUOTE=lemming77;20754656]I'd say typedefs and includes should go in the header files, since then they can be used from everywhere else. But definitions I'd advise you to seperate into source files.

[editline]03:42AM[/editline]

Oh wait, by defines, you mean #define preprocessor statements right? Yeah, I'd put them in headers too, just so they're declared before they're used.[/QUOTE]

Includes go in the header file if they are used within the header file. If you use std::string in your .cpp, but you declare no functions or define no classes that use std::string in your header, then you should include only in your .cpp.

[Agent766]

Make sure to use include guards.

#pragma once

at the the top of the header, or

#ifndef WHATEVER
#define WHATEVER
...
#endif