optional data and if statements

lajkonik86

i tend to put my program full of code which takes into account the fact that maybe there is no data.

For instance a logo for a company. Instead of just putting out the logo, i first check if there is a logo.
If(logo==1) echo.........

Sometimes I just put the entire html in an variable and simply leave it empty when no data is present.

These are just two ways of dealing with this, but i suppose there have to be better approaches... Anyone?

scross

That's a good coding style 🙂
Anyway, the best thing to do is put the variable equal to false, and then to check whether you can use it/whether it exists use:

if($variable !== false){

which should work every time.

lajkonik86

true, but on the negative side that will probably leave you with a lot of almost duplicate lines.
is there a cleaner way?

scross

lajkonik86 wrote:
that will probably leave you with a lot of almost duplicate lines.

Why is that? ...

laserlight

If you know that the data is supposed to be within a particular range of values, then you might want to check that. In fact, if the data is an incoming variable, you should check with [man]isset/man or [man]empty/man before using it.

scross' suggestion has a slight bug. By comparing for equality with false, you actually get false positives when the variable is null. It may be better to check with empty() instead, but then you have to know that 0 is not a valid value (otherwise you would get a false negative instead).

scross

I was just using the value of false as a marker that the variable should not be used (would be set earlier in the script).

Weedpacket

I'd use null for that purpose, myself; returns false for isset(), but can be used without throwing notices, return true for is_null(), is distinctive and unique (there is only one null), and explicitly means an "absence of value".