Do you prefer “if (var)” or “if (var != 0)”? [closed]

Answer 1

If i don't expect anyone else to read the code, I'd us the short one. If I expect someone to actually read my code, I would consider using the long form for readability.

Answer 2

If you've got an int-bool in C that already holds a flag (and not a count), and you're testing it with "if (var != 0)", where does it end? Wouldn't "if ((var != 0) != 0)" be even better? :-)

Answer 3

I prefer explicit tests unless the result inside the parentheses is a explicit boolean. The phrase "if (1)", while syntactically and semantically correct in terms of the language, is not logical. It should be true or false, not cast automatically.

I prefer readable logical code to less typing any day.

I also despise vehemently code of the form:

if (gotError == FALSE) ...
if (isComplete == TRUE) ...

If the boolean value is properly named (and it should be), the right way to do that is:

if (!gotError) ...
if (isComplete) ...

That's because (using reductio ad absurdum) boolVal == TRUE is simply another boolean value, so where do you stop?

if (isComplete == TRUE) ...
if ((isComplete == TRUE) == TRUE) ...
if (((isComplete == TRUE) == TRUE) == TRUE) ...
if ((((isComplete == TRUE) == TRUE) == TRUE) == TRUE)...

And so on, ad infinitum.

Answer 4

For numeric value scalars, I tend to write if ( $num_foo ) when $num_foo is in my control. If it’s user input or passed in from outside I either numify it first or spell out the test explicitly. It depends on a lot of factors. The main criterion is when and how it’s convenient to deal with undefined values, in order to avoid warnings.

To test for non-empty string, I used to write if ( $foo ) because the correct incantation is just way too much typing:

if ( defined $foo and length $foo )

But I wasn’t satisfied with this state of affairs so I instigated a change of behaviour for length undef in Perl 5.12, which throws a warning and returns 0 up to Perl 5.10 inclusive. In 5.12 it will just silently return undef. Therefore in non-boolean contexts you still get a warning, it just happens after the length call is evaluated rather than before. But in boolean contexts, there is no warning, so checking for a non-empty string is much easier to do correctly:

if ( length $foo )

Answer 5

I have a bunch ways of doing it:

for booleans:

if (x)

for ints:

if (x != 0)  // always compare, never assume true/false on int values

for pointers:

if (x /* != 0 */)  // I've always done this, not sure where I picked it up but I like it

These days, I think it's nicer to have a function call which describes what the logic actually means within the if statement

EDIT: Note, the 0 (intsead of NULL) is because I mainly use C++ these days

Answer 6

I like my ifs to make sense when read aloud:

if (is_it_happening) ...
if (number_of_sheep != 0) ...
if (pointer_to_something != NULL) ...