Archive for February, 2009

if-statements – checking strings for being null

12. Feb, 2009  No Comment

hello again!
Yesterday I wrote some code again and had to check if a String is null or not. The check was performed in a for-loop.
Below is some example code:

public var arrToFill:Array = [];
[... some more code here ...]
private function foo():void
{
  var i:uint;
  for( i = 0; i < 10; ++i)
  {
    if(!arrToFill[i])
    {
      arrToFill[i] = '';
    }
  }
}

This function was called different times and I wondered, that the if-statement returned false everytime.
For me it was theoretically correct that an Array-Element with a value of ” is not empty, because ” is an empty String for me, but it is something.
ActionScript3 doesn’t work like that, so for AS3 a String with a value of ” is equal to null or 0.

Conclusion:
If you have code like this and want to preallocate an element, just set it to 1. Then you can do a simpy 

if(!arrToFill[i])

and everything would be fine.

[TIDY UP YOUR CODE] :: if – elseif – elseif – elseif – else

6. Feb, 2009  No Comment

I thought about doing an extra section called ‘TIDY UP YOUR CODE’.
From time to time I will post some tips how you can write reader-friendly code.
So Let’ start with the first topic: if – elseif – elseif – elseif – else

Have you ever seen something like this ?

if(expressionA)
{
  .. do something ..
}
elseif(expressionB)
{
  .. do something else..
}
elseif(expressionC)
{
  .. do something else..
}
elseif(expressionD)
{
  .. do something else..
}
else
{
  .. do something else..
}

Code like this is hard to read, don’t you agree with this?
TIDY IT UP! Use a switch instead:

switch(true)
{
  case expressionA:
  {
	.. do something ..
  }; break;
 
  case expressionB:
  {
	.. do something else ..
  }; break;
 
  case expressionC:
  {
	.. do something else ..
  }; break;
 
  case expressionD:
  {
	.. do something else ..
  }; break;
 
  default:
  {
	.. do something else ..
  }; break;
}

In my opinion this is great :-}

Prevent using long if-expressions

6. Feb, 2009  1 Comment

Hello out there!
Today I learned how to check a lot of statements in one expression, but without having unreadable code like that:

if(this.strChar == 'a' || this.strChar == 'b' || this.strChar == 'c')
{
  .. do something ..
}

What you can do instead is creating an unnamed Array, push the values into it and then check if the Array contains one of those values.
Let’s see:

package
{
  pubilc class foo
  {
    public function foo(strChar:String = 'default'):Boolean
    {
      if(['one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'default'].indexOf(strChar) >= 0)
      {
        return true;
      }
      return false;
    }
  }
}

i suppose that most of the code should be understandable to you, but let’s take a look at the if-statement:

if(['one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'default'].indexOf(strChar) >= 0)

You could also use the following code with the same result:

var arrStringNumbers:Array = new Array();
arrStringNumbers.push('one', 'two', 'three' /*and so on... */);
 
if(arrStringNumbers.indexOf(strChar) >= 0) // give me the index of strChar (if arrStringNumbers does not contain strChar, we get -1 as result, so the if-statement is false)