Logical Operators

danielson2k

Could someone tell me why:

if($file != "." || $file != "..")

doesnt work, but

if($file == "." || $file == "..")

works fine?

Any ideas on how I can get this working?

Muchos thanks.

Tigress7

have you tried !== , just a thought, not even sure if it exists, but i woulda figured that now it was saying 'not equal'..

tekky

Originally posted by Tigress7
have you tried !== , just a thought, not even sure if it exists, but i woulda figured that now it was saying 'not equal'..

!== is boolean compare, it will not only compare, but for functions that return FALSE, it will not match FALSE == 0 (zero) as true

And to the start of this....

it all depends on the context you need them used in....

if ($file != '..' || $file != '.') //will match as long as $file doesnt 
{
     //this is not .. or . so we will echo the file name
     echo $file;
}

if ($file == '..' || $file == '.') //will match if $file it equals . or ..
{
     //this is . or .. so we will do nothing
}
else
{
     //this isnt . or .. so we will echo it
     echo $file;
}

danielson2k

Yeah, ive given that a go, !== is pretty much the same as != but checks to see if whats being compared is equal and of the same type.

There are ways round this so its not like im totally stuck or anything, but id be interested to know what to do to fix it.

Thanks for the help 🙂

danielson2k

Originally posted by tekky
!== is boolean compare, it will not only compare, but for functions that return FALSE, it will not match FALSE == 0 (zero) as true

And to the start of this....

it all depends on the context you need them used in....
if ($file != '..' || $file != '.') //will match as long as $file doesnt 
{
     //this is not .. or . so we will echo the file name
     echo $file;
}

if ($file == '..' || $file == '.') //will match if $file it equals . or ..
{
     //this is . or .. so we will do nothing
}
else
{
     //this isnt . or .. so we will echo it
     echo $file;
}
[/B]

One way round it is:


if($file != "."){

    if($file != ".."){

            echo($file."<br>");

    }

}

PHP doesnt seem to like the combination of != and ||

Weedpacket

It's a silly test, because it will always be true: $file is either not '.' or not '..', and it can't exactly go around being both.

If you're wanting to ensure that $file is neither '.' nor '..' then you should say that it's not '.' or '..'

if(!($file=='.' || $file=='..'))

which can be simplified (basic logic) to

if($file!='.' && $file!='..')

Which obviously says "if $file is not '.' AND $file is not '..'.