Probolem with returning array values from finction.

[morgan]

#include<conio.h>
#include<stdio.h>
#include<iostream.h>
#define re 1 //realis
#define im 2 //imaginalis

typedef int complex;

complex F1 (complex x[2],complex y[2]){
cout<<"Dodawanie liczb zespolonych"<<
"("<<x[re]<<"+"<<x[im]<<"i)+"<<"("<<y[re]<<"+"<<y[im]<<"i)=";
complex z[2];
z[re]=x[re]+y[re];
z[im]=x[im]+y[re];
return z;} // <========Here



void main()
{clrscr();
complex x[2],y[2];
cout<<"Podaj liczbe rzeczywista do pierwszej liczby zespolnoej x+yi x= ";
cin>>x[re];
cout<<"Podaj liczbe urojon¡ do pierwszej liczby zespolnoej x+yi y= ";
cin>>x[im];
cout<<"Podaj liczbe rzeczywista do drugiej liczby zespolnoej x+yi x= ";
cin>>y[re];
cout<<"Podaj liczbe urojon¡ do drugiej liczby zespolnoej x+yi y= ";
cin>>y[im];
complex z[2];
z=F1(x,y); // <========And here


cout<<"("<<z[re]<<"+"<<z[im]<<"i)"<<endl;
getchar();
}

 

[Peter Koch Larsen]

#include<conio.h>
#include<stdio.h>
#include<iostream.h>
#define re 1 //realis
#define im 2 //imaginalis

typedef int complex;

complex (most surprisingly!) is an int.

complex F1 (complex x[2],complex y[2]){
cout<<"Dodawanie liczb zespolonych"<<
"("<<x[re]<<"+"<<x[im]<<"i)+"<<"("<<y[re]<<"+"<<y[im]<<"i)=";
complex z[2];
z[re]=x[re]+y[re];
z[im]=x[im]+y[re];
return z;} // <========Here

Here you return what effectively is a pointer to int.
Why not use the built-in complex?

/Peter
[snip]

 

[Tim Love]

Your F2 function returns a pointer (though your code makes it look as
if you expect it to return something else) to an area of memory that
is freed when the function finishes. The area of memory will be
re-used sooner or later.

Use C++'s complex numbers, or "new", etc.

complex z[2];

This makes z a const. Maybe you mean "complex *z"? But you need to change
other things too.

 

[Dave O'Hearn]

#include<conio.h>
#include<stdio.h>
#include<iostream.h>
#define re 1 //realis
#define im 2 //imaginalis

This part is wrong. Arrays start at 0, not 1, so you need,

#define re 0 //realis
#define im 1 //imaginalis

For the rest, I'd consider using std::complex<int>. You could also make
your own data structure holding a real and imaginary, but std::complex
will do this for you.

 

[E. Robert Tisdale]

complex (most surprisingly!) is an int.

In the context of a computer programming language
for finite precision digital computers,
the terms complex and real simply distinguish subsets
of the real number line and the complex plane respectively.

 

[Richard Herring]

This part is wrong. Arrays start at 0, not 1, so you need,

#define re 0 //realis
#define im 1 //imaginalis

For the rest, I'd consider using std::complex<int>.

I emphatically wouldn't.

26.2/2: The effect of instantiating the template complex for any type
other than float, double or long double is unspecified.

You could also make
your own data structure holding a real and imaginary, but std::complex
will do this for you.

But complex<int> may behave in ways you wouldn't expect.

 

[Peter Koch Larsen]

In the context of a computer programming language
for finite precision digital computers,
the terms complex and real simply distinguish subsets
of the real number line and the complex plane respectively.

Is that so? My belief was that seeing the typename "complex" in any
programming language was a hint that there would be a real and an imaginary
part.

/Peter