Where to put comments in an IF THEN ELSE construct
I never decided on what the best way is to comment IF-THEN-ELSE constructs, so I never standardized on a consistent way to comment them. I appreciate any insights.
Some options:
a)
IF (blabla) {
// this comment explains what happens in the IF case
dothis();
} else {
// this comment explains what happens in the ELSE case
dosomethingelse();
}
drawback: in case of multiple dothis() statements, I like to comment the major blocks, and in that case it isn't always clear if the IF-comment belongs to the first dothis() block or to the whole IF case
or b)
IF (blabla) { // this comment explains what happens in the IF case
dothis();
} else { // this comment explains what happens in the ELSE case
dosomethingelse();
}
drawback: only works for short comments. I usually comment IF-THEN-ELSE constructs if the IF and ELSE case isn't directly clear from the code, which typically requires a comment longer than one line.
or c)
// if the following happens
IF (blabla) { // then do this
dothis();
} else { // or else do this
dosomethingelse();
}
PS: I know about "the code should be self explanatory", but this isn't always the case...
For me, a comment above the IF explains the IF statement itself. For example, if the condition being tested is particularly complex.
A comment in the block below the IF or ELSE describes what's going once the condition has been evaluated and a choice made.
So like this:
//Is this a favoured customer and do we have a promotion?
if customer.special() and monthly.hasOffer() {
//Add discount
invoice.addDiscount();
}
else {
//Add note about favoured customer scheme
invoice.addNotes(JOIN_OUR_DISCOUNT_SCHEME);
}
I never gave it very much thought; personally and when required I have put comments above the IF and ELSE statements. This gives me nice separation between the comments about the branch statements and comments about the code.
// comment about the if statement
if (expression)
{
// comment about the code
doSomething();
}
// comment about the else statement
else
{
// comment about the code
doSomethingElse();
}
I also note that I am the only answer so far to use the "open curly brace style", which might be a throw back to my Pascal days although I do prefer the visual justification of begin and ends of code blocks, so my comment style may not work for the "closed curly brace style community.
我会做案例a），但有一点额外的空白：
if (blabla) {
// This explains the whole if case
// Can comment here for specific block comments
doThis();
} else {
// This explains the else case
// Same again
doSomethingElse();
}
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