Programming preference - use else ifs with multiple return statements? [closed]

Answer 1

If a function has multiple "successful" return values, I'll use if/else to select among them. If a function has a normal return value, but one or more ways that may abnormally exit early, I generally won't use an "else" for the normal path. For example, I think it's far more "natural" to say:

int do_something(int arg1)
{
  if (arg1 > MAX_ARG1_VALUE)
    return ARG1_ERROR;
  ... main guts of code here
  return 0;
}

than to say:

int do_something(int arg1)
{
  if (arg1 > MAX_ARG1_VALUE)
    return ARG1_ERROR;
  else
  {
    ... main guts of code here
    return 0;
  }
}

or

int do_something(int arg1)
{
  if (arg1 <= MAX_ARG1_VALUE)
  {
    ... main guts of code here
    return 0;
  }
  else
    return ARG1_ERROR;

This distinction becomes especially significant if there are multiple things that can "go wrong", e.g.

int do_something(int arg1)
{
  if (arg1 > MAX_ARG1_VALUE)
    return ARG1_ERROR;
  ... some code goes here
  if (something_went_wrong1)
    return SOMETHING1_ERROR;
  ... more code goes here
  if (something_went_wrong2)
    return SOMETHING2_ERROR;
  ... more code goes here
  if (something_went_wrong3)
    return SOMETHING3_ERROR;
  return 0;
}

Nested 'if/else' statements in such cases can get ugly. The most important caveat with this approach is that any cleanup code for early exits must be given explicitly, or else a wrapper function must be used to ensure cleanup.

Answer 2

In this case it is more clear. In the general case you may want to leave the elses off as they can contribute to more nesting and code complexity. For example:

if (error condition) {  
  do some stuff;
  return;
} else {
  do stuff;
  if (other error condition) {
     do some stuff1;
     return;
  } else {
     do some other stuff;
     return

  }
}

The code below keeps the level of nesting down which reduces code complexity:

if (error condition) {
  do some stuff;
  return;
}
do stuff;
if (other error condition) {
  do some stuff1;
  return;
}
do some other stuff;
return;

In your example it is easy either way. But in many cases you would be better off using a lookup table for this sort of thing and reading the values from a file/database. For efficiency in C often this would be coded as an array of structs.

The else does add some clarity in that it makes it clear that the cases are mutually exclusive. However the idiom of returning like you do is obvious to many programmers, so either way the majority will know what you meant.

I can think of an advantage of the elses. If you want to add a new last case, without the elses you might forget to add an if to the currently "Too Hot Condition" if say you wanted to add "Dying" at 120 or something. while with the elses you know that you need the final else to be in front of "Dying" so you will be more likely to think about putting the else if in front of "Too Hot". Also if you just put an else on "Dying" you will get a compile error which forces you to think.

Answer 3

it's good. without "else", this line

if(temp < 80)
    return "Comfortable";

would be unconvincing. with "else", it's clear that there are other preconditions.

Answer 4

I prefer case statements myself but that would make this a language specific topic and not language-agnostic topic.

    Dim Temp As Integer
    Dim Message As String

    Select Case Temp
        Case Is < 32
            Message = "Freezing"
        Case Is < 60
            Message = "Just Right"
        Case Is < 80
            Message = "Too Hot"
        Case Else
            Message = "What was I doing?"
    End Select

I find these alot easier to read then if..else statements.