macro

[mar11]

Hi all,

i have the following example

#include <iostream>

#define ADD(a,b) for(int i=0;i<100;i++) (a= b+i)

int main{
int a(0),b(0),c;

c= ADD(a,b);
cout << c;

return 0;

}

i can not compile this code because of the for statement-i guess-

how could for statment implemented in macro?

[chrisname]

It isn't going to work.

Do you know what the preprocessor does?
It replaces all instances of what you defined with the value.
So this:
c= ADD(a,b);
is really:
c = for(int i=0;i<100;i++) (a= b+i);
after the preprocessor is done.

Also your return statement will not work. You need a space between the keyword and the '0'.

[Duthomhas]

Why is there suddenly a slew of people posting silly macro questions?

Use a function.

int ADD( int a, int b )
  {
  for (int i = 0; i < 100; i++)
    a = b + i;
  return a;
  }

One thing to note: the function you wrote is the same as:

int ADD( int a, int b )
  {
  return b + 99;
  }

Also, if you intend for the argument values to be affected, you need to make them references:

int ADD( int& a, int b )
  {
  a = b + 99;
  return a;
  }

Et cetera.

Finally, watch your syntax. When programming, there is no room for ommissions or variations.

#include <iostream>
using namespace std;

int ADD( int& a, int b )
  {
  a = b + 99;
  return a;
  }

int main()
  {
  int a = 0;
  int b = 0;
  int c;

  c = ADD( a, b );

  cout << "a = " << a << endl;
  cout << "b = " << b << endl;
  cout << "c = " << c << endl;

  return 0;
  }

Hope this helps.