What to put in the IF block and what to put in the ELSE block?

Question

This is a minor style question, but every bit of readability you add to your code counts.

So if you've got:

if (condition) then
{
   // do stuff
}
else
{
   // do other stuff
}

How do you decide if it's better like that, or like this:

   if (!condition) then
   {
     // do other stuff
   {
   else
   {
     // do stuff
   }

My heuristics are:

1. Keep the condition positive (less mental calculation when reading it)
2. Put the most common path into the first block

Answer 1

I prefer to put the most common path first, and I am a strong believer in nesting reduction so I will break, continue, or return instead of elsing whenever possible. I generally prefer to test against positive conditions, or invert [and name] negative conditions as a positive.

if (condition)
    return;

DoSomething();

I have found that by drastically reducing the usage of else my code is more readable and maintainable and when I do have to use else its almost always an excellent candidate for a more structured switch statement.