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I hate OOP, please give me assistance

hhjkkh10 (20)
I loved procedural programming last year, i understood the syntax and everything. OOP is such a step forward, for example i have an assignment where i have to do matrix addition using classes, i just don't understand it whatsoever, even after looking through websites etc to try and understand it. This is scary considering i wanna be a software engineer when i'm older...
Hippogriff (727)
Post the code you have so far and explain exactly where you get confused so we can help with that.

Do you know how to define a class? How to create methods/variables in a class? How to create/use class objects? I think the responses on your other thread give some good explanations to start off with.

http://www.cplusplus.com/doc/tutorial/classes/
Last edited on
Duthomhas (13119)
You are told OOP is significantly different than procedural programming.

It isn’t.

Procedurally, you create things (objects) and then have functions that operate on those objects.

In OOP, the functions that operate on objects are just part of the object.

For example:

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struct point
{
  double x, y;
};

point create_point( double x, double y )
{
  point p;
  p.x = x;
  p.y = y;
  return p;
}

void add_point( point& a, point b )
{
  a.x += b.x;
  a.y += b.y;
}

etc
 
struct point
{
  double x, y;


  point( double x, double y )
  {

    this->x = x;
    this->y = y;

  }

  void add( point b )
  {
    this->x += b.x;
    this->y += b.y;
  }

  etc
};

They get used similarly:
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int main()
{
  point p = create_point( -7, 3.1415926 );
  add_point( p, create_point( 2, 0 ) );
  cout << p.x << "," << p.y << "\n";
 
int main()
{
  point p { -7, 3.1415926 };
  p.add( point( 2, 0 ) );
  cout << p.x << "," << p.y << "\n";

What OOP provides you, though, is additional super powers over resource management.

For example, in C, playing with files requires careful awareness of whether or not your program has an open file handle:

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  FILE* fp = fopen( "somefile.csv", "r" );
  if (!fp) return false;

  int foo, bar, baz;
  if (!fscanf( fp, "%d %d %d", &foo, &bar, &baz ))
  {
    fclose( fp );
    return false;
  }

  if (...)
  {
    fclose( fp );
    do_some_other_cleanup();
    return false;
  }

  ...
  // everything's good, phew...
  fclose( fp );
  return true;

C++ encapsulates all that worry into the object's automatic destructor.

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  std::ifstream f( "somefile.csv" );
  if (!f) return false;
  
  int foo, bar, baz;
  f >> foo >> bar >> baz;
  if (!f) return false;

  if (...)
    return false;

  ...

  // finally...
  return true;

The convenience here is that the fstream object knows how to clean up after itself.

OOP also provides you with better control over what your users can do with your objects. In procedural programming you have to go through some extraordinary measures to hide information the user shouldn't be touching. Most of the time, you just have a comment that says "don't touch this" and hope your users don't. (They do.)

OOP lets you mark stuff as “public” or “private” (or “protected”, which is private to everything except derived classes).

This is part of information hiding and data abstraction.


There’s more, but that should get you started.

Don’t think of OOP as evil. It is just looking at things from a slightly different angle. Consider if the “point” class above were a “matrix”. Complete with operator overloads, you can very easily create matrices.

Hope this helps a little...
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