What is Wrong with my code ❓

Question

include <iostream.h>
include <conio.h>
class complex
{
float real,img;
public:
void assign(float x,float y)
{
real=x;
img=y;
}
void print()
{ if(img>=0)
cout<<real<<"+"<<img<<"i";
else
cout<<real<<img<<"i";
getch();
}
};
void add( float a,float b,float c, float d)
{

float e,f;complex g;
e=a+c;
f=b+d;
g.assign(e,f);
g.print();
}
void sub( float a,float b,float c, float d)
{

float e,f;complex g;
e=a-c;
f=b-d;
g.assign(e,f);
g.print();
}
void mul( float a,float b,float c, float d)
{

float e,f; complex g;
e=a*c-b*d;
f=b*c+a*d;
g.assign(e,f);
g.print();
}
void main()
{
float a,b,c,d;
complex x,y,z;
clrscr();
cout<<" for complex 1:";
cout<<"real part:";
https://code.sololearn.com/coLFDkeQVjRU/?ref=app

Answer 1

Use of non-standard functionality, mostly. <iostream.h> has long been replaced by <iostream>, and <conio.h> is outdated and has never been standard in the first place. The main() function must return an integer too.
Moreover, preprocessor directives like include need to start with a # in front of them.
Also, all things from the Standard Library are encapsulated within the std namespace, therefore you either have to specify that directly when calling them, e.g. std::cout << ..., std::cin >> ..., etc., or you have to import the namespace, i.e.
using namespace std;
You can also choose to import only parts of it, e.g.
using std::cout;
using std::cin;
...

https://code.sololearn.com/c3xO4MvJkR62/?ref=app

Answer 2

Thanks for the useless C# tag.