Optimize IF condition block

Question

this is my first post here!
How can i optimize the if condition on this snippet?

The only one difference is && [self isCurrentPosition:i].
How can made it on a single if, including the condition val?

- (void) cleanTextfieldExcluding:(int)current checkPosition:(BOOL)val {
  for ( int i=0; i<[self count]; i++ ) {

    // -----------
    if ( val ) {  // this IF block is very bad
      if ( i != current && [self isCurrentPosition:i] )
        [self replaceObjectAtIndex:i withObject:@""];
    } else {
      if ( i != current ) 
        [self replaceObjectAtIndex:i withObject:@""];
    }
    // -----------

  }
}

Note: self is a category of NSArray.

thanks.

namehere · Accepted Answer · 2012-11-28 15:31:25Z

up vote 2 down vote accepted

It seems that the code in if will be executed only if i != current and val && [self isCurrentPosition:i] or !val, so you could merge all the ifs into one:

- (void) cleanTextfieldExcluding:(int)current checkPosition:(BOOL)val {
  for ( int i=0; i<[self count]; i++ ) {

    // -----------
    if ( (i != current) && (!val || [self isCurrentPosition:i]) ) {
        [self replaceObjectAtIndex:i withObject:@""];
    }
    // -----------

  }
}

edited Nov 28 '12 at 15:31

answered Nov 28 '12 at 11:28

namehere
1796

	+1. perfect way! – elpsk Nov 28 '12 at 11:49
	just saw the answer below me and OMG it was better than mines(performs one less logic operation) so i updated mines too. :P – namehere Nov 28 '12 at 15:32
	-1. Your answers are now the same because you copied his code (and didn't upvote his answer). – seand Nov 28 '12 at 16:29
	oops sorry. i forgot to upvote it. just did it. – namehere Nov 28 '12 at 16:30

Val · Answer 2 · 2012-11-28 12:39:23Z

the (val · ¬cur · pos) | (¬val · ¬cur) = ¬cur (val·pos | ¬val) = ¬cur (pos | ¬val). So, the condition is

if ( (i != current) && (!val || [self isCurrentPosition:i]) ) {
        [self replaceObjectAtIndex:i withObject:@""];
    }

You just must practise factoring out the common subexpressions and subprograms and learn how to use the Carnot maps for boolean minimization.

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Optimize IF condition block

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