Ugliest function I've ever written (C++):

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jread
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Joined: 9 Nov 2005
Age: 45
Gender: Male
Posts: 138
Location: Austin, TX

05 Nov 2007, 2:27 pm

DISCLAIMER: I am in no way responsible if blood starts shooting from your eyes after looking at this!

So, this is what happens when you stay up all night writing a program that's due the next day because you're a procrastinating bastard. I needed a function that read a polynomial from a linked list (each node had data elements for coefficient and power), then printed them to the screen in the correct format. I wrote this one on the first pass and while it's horrid, it did the job and I didn't have enough time to refine it.

Code:

void printList()
      {
         Node *Walker;
         Walker = pHead;
         while (Walker != NULL)
         {
            if (Walker->power != 0)
            {
               if (Walker->coeff > 0)
               {
                  if (Walker == pHead)
                     cout << Walker->coeff << "x" << "^" << Walker->power;
                  else
                  {
                     if (Walker->power > 1)
                        cout << "+" << Walker->coeff << "x" << "^" << Walker->power;
                     else
                        cout << "+" << Walker->coeff << "x";
                  }
               }
               else
               {
                  if (Walker->power > 1)
                     cout << Walker->coeff << "x" << "^" << Walker->power;
                  else
                     cout << "+" << Walker->coeff << "x";
               }
            }
            else
            {
               if (Walker->coeff > 0)
                  cout << "+" << Walker->coeff;
               else
                  cout << Walker->coeff;
            }
            Walker = Walker->next;         
         } 
      }      
};

Fuzzy
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06 Nov 2007, 2:27 am

Spagetti much?

Its not too bad!

ahayes
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06 Nov 2007, 11:59 am

I've written worse until I figured out switch-case in C.

TheZach
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06 Nov 2007, 2:26 pm

Hey, s**t happens. Look at windows.

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TheBladeRoden
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06 Nov 2007, 5:37 pm

What does it do? It seems to involve some guy named Walker a lot.

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lau
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06 Nov 2007, 8:39 pm

Changing whitespace and replacing "Walker" with "W", as a long variable name is merely clutter in a short piece of code...

Code:

void printList() {
  Node *W;
  W = pHead;
  while (W != NULL) {
    if (W->power != 0) { 
      if (W->coeff > 0) { 
        if      (W == pHead)   cout <<        W->coeff << "x" << "^" << W->power; 
        else if (W->power > 1) cout << "+" << W->coeff << "x" << "^" << W->power; 
        else                   cout << "+" << W->coeff << "x";      
      } else {
        if (W->power > 1)      cout <<        W->coeff << "x" << "^" << W->power;
        else                   cout << "+" << W->coeff << "x"; 
      }
    } else {
      if (W->coeff > 0)        cout << "+" << W->coeff;
      else                     cout <<        W->coeff;
    }
    W = W->next;         
  }      
}
}; 

There's the extra close brace, which might be a copy/paste slip.

There's a question... although x^0 is unity (when x is not zero), is this really part of the requirement, to drop "x^0" from the expression? In which case, you should also test for "W == pHead" in the second section, to also avoid the spurious prefixing of a "+" sign.

Also, the "+" is wrong in the fifth "cout" line.

From your description, I assume that "power" is unsigned. Even so, I would be tempted to use "W->power" != 1", just so negative powers would not be dropped. It will suffice, whether the field is signed or unsigned.

Anyhow, my pet hate is the current trend of using a code layout that completely obscures everything.

An alternative version would be...

Code:

void printList() {
  Node *W;
  char *p = ""; // don't need infix "+" at the start
  for (W = pHead; W != NULL; W = W->next) {
    if (W->coeff > 0) cout << p;
    p = "+"; // from now on, may need to force an infix "+"
    cout << W->coeff;
    if (W->power != 0) {
      cout << "x"; 
      if (W->power != 1) cout << W->power;
    }
  }
}

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lonelyLady
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13 Nov 2007, 8:46 pm

a dumb question: what does '->' do? I took a c++ programming course but I've never seen this one. Thanks!

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lau
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13 Nov 2007, 8:58 pm

lonelyLady wrote:

a dumb question: what does '->' do? I took a c++ programming course but I've never seen this one. Thanks!

"a->b" is an alternative for "(*a).b"
where "a" is a pointer to an instance of a structure with a member named "b".
In the same vein as "a[b]" is equivalent to "(*(a+b)))".

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Last edited by lau on 14 Nov 2007, 4:58 pm, edited 1 time in total.

MysteryFan3
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13 Nov 2007, 10:35 pm

For a last-minute jam session, that's pretty good code. I've seen really old unreformatted COBOL code that would curl anyone's hair.

I wrote a program in Unisys BPL once to try out some stuff. I didn't bother with formatting since it wasn't written for production. It was pretty ugly. It became a utility program so I ended up having to reformat and document it. I was more careful after that.

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