Should I use return/continue statement instead of if-else?

Question

In C, C++ and C# when using a condition inside a function or loop statement it's possible to use a continue or return statement as early as possible and get rid of the else branch of an if-else statement. For example:

while( loopCondition ) {
    if( innerCondition ) {
        //do some stuff
    } else {
        //do other stuff
    }
}

becomes

 while( loopCondition ) {
    if( innerCondition ) {
        //do some stuff
        continue;
    }
    //do other stuff
}

and

void function() {
    if( condition ) {
        //do some stuff
    } else {
        //do other stuff
    }
}

becomes

void function() {
    if( condition ) {
        //do some stuff
        return;
    }
    //do other stuff
}

The "after" variant may be more readable if the if-else branches are long because this alteration eliminates indenting for the else branch.

Is such using of return/continue a good idea? Are there any possible maintenance or readability problems?

Solution 1

The compiler will almost certainly generate the same code. Even if it didn't, the difference will be probably irrelevant. Hence, the relevant argument is certainly how people would read it.

Therefore the question is how similar "//do some stuff" and "do other stuff" are. If they are conceptually similar, use if/else. If they're conceptually different, use continue/return.

Solution 2

My personal approach of choosing one is that if the body of the if part is very short (3 or 4 lines maximum), it makes sense to use the return/continue variant. If the body is long, it's harder to keep track of the control flow so I choose the else version.

As a result, normally, this approach limits the usage of return/continue style to skip some data and avoid further processing rather than process this using one of the following methods (which is better suited by if/else).

Solution 3

The code would be more readable if termination criteria are handled first. I always prefer, checking for conditions that require a break or return rather than those that would need lengthy code execution. I prefer:

 if (termination condn) 
      return;
 // code 
 // code

to

if (success condn)
{
  // code
  // code
}
else
 return;

This makes reading and understanding the code easier.

Solution 4

It depends a little on how long the branches are. The use of return/continue that you describe is good if the initial if check is short, and the body is long. If both if and else parts are long, I would extract them to separate functions.

I recommend reading Code Complete, it discusses things like this a lot.

Solution 5

The glib answer is that it all depends.

My general feeling is that if condition is a rare, guard (e.g. check for null) or error condition then I tend to use return or continue

If it's an expected case then I tend to use your first approach.

Notice, however, that I said "tend". The boundary between these to conditions is vague and subject to change depending on the project and who I'm working with.

View more solutions