the infamous 'needless else' (idea)

A related needless if...else that I frequently encounter in computer programing code concerns the use of Boolean variables. Many of us program in languages such as Java, C#, Delphi and others where boolean is a built-in type that can only take the values True and False. Even those who program in C/C++ where a Boolean is just a disguised integer may encounter the same needless else and can apply the same remedy.

To rework kaatunut's example using the boolean type, the needless else occurs in code such as

bool IsFive(int a)
{
  if (a == 5)
    return true;
  else
    return false;
}

The if statement in all these languages requires its test to be an expression that evaluates to a boolean. So this statement says roughly: "evaluate some boolean condition, and it is true, return true, else if it is false, return false." This can be expressed more simply as "evaluate some boolean condition, and return it". In code:

bool IsFive(int a)
{
  return (a == 5);
}

Similarly you might see code in larger procedures which can be simplified, e.g.

  ...

  if ((a == 5) && (b == 4))
    IsFiveAndFour = true;
  else	
    IsFiveAndFour = false;

  ...

Naturally, you will occasionally have to reverse the sense of your test, e.g.

bool IsNotFive(int a)
{
  if (a == 5)
    return false;
  else	
    return true;
}

becomes

bool IsNotFive(int a)
{
  return (a != 5);
}

In doing more complex sense-changing, DeMorgan's Laws may be of use.

Here's a slightly more complex case taken from some Delphi code that I worked with, where the line count is reduced from 7 to 3.

  if AnEngine.Error <> '' then
  begin
    ShowErrorMessage(AnEngine.Error);
    Result := False;
  end
  else
    Result := True;

becomes

  Result := (AnEngine.Error = '');
  if not Result then
    ShowErrorMessage(AnEngine.Error);

Is the shorter version better code? In my opinion, yes. I do not care about saving a few bytes in the size of the source code - disk space is dirt cheap. Source code readability is a much more important goal, and concise code is readable. The effect on the resulting program is also important. While premature optimisation is a bad thing, coding in an efficient manner from the outset is a good idea.