Hello

I have a IF ELSE problem

I need to display pictures of some products. Some products have like 10 pictures and other products only 1 or 2.
What i did is:
IF the picture exists then concat to get the full path to the image.
ELSE display a background image.
$picture1 is a string containing the name of the gif file
$string1 is a string containing the full path to the gif file

if ($picture1 != "")
{
$string1="img/" . $picture1;
} else {
$string1="img/back.GIF";
}

Problem is it only executes the ELSE statement. So now I get all my pictures as "back.GIF"
What am I doing wrong?

flish,

First, your IF condition doesn't check to see "if the file exists," but only if the string that should point to the image is equal to the empty string. If that is the condition you want to check, I would suggest you use the empty() function. Also, you can integrate $picture1 into the string without concatenation (if you prefer - it looks cleaner).

PHP Code:


if( empty( $picture1 ) )
{
    $string1 = "img/back.gif";
}
else
{
    $string1 = "img/$picture1";
} 


Or, since you are doing an if/else assignment, the tertiary operator especially lends itself here.

PHP Code:


$string1 = empty( $picture1 ) ? "img/back.gif" : "img/$picture1"; 


Thank you very much. It worked perfectly. I still dont know what I did wrong but practice makes perfect

"First, your IF condition doesn't check to see "if the file exists," but only if the string that should point to the image is equal to the empty string" - Exactly what I had in mind, only my english is not very good

flish, no problems. The only problem with checking for an empty string in the manner you did was that it does not catch the use case when the string is equal to null. That's why the empty() function is so useful in that case because it checks for both contingencies.

Using functions is actually a lot slower than doing things without using functions.

If I was checking for an empty string or something this is what I would do:

PHP Code:

<?php

$string1 = ($picture1 == TRUE) ? 'img/' . $picture1 : 'img/back.gif';

?>

Because the variable is not inside quotes this will also speed things up. At the end of the day you want things to be as fast as possible so that your processor is not wasting its time doing pointless things.

Originally Posted by Bon Bon

Using functions is actually a lot slower than doing things without using functions.

I am not sure the basis for your assertion, but I would offer in respectful opposition that in tasks where the number of instructions is limited (and let's face it, most PHP scripts use to build web pages are exactly that), the amount of time saved by avoiding functions is so miniscule that it is rendered irrelevant.

Functions made available by the PHP scripting language itself can be assumed to be optimized for their purposes and their cost minimal.

Again, I would be interested in any references you have showing functions to be inherently slower than in-line code.

Unless you have a crazy amount of page requests, the function call overhead will make no difference at all. If you were batch processing millions of images, then I can understand, but for one, you won't notice the difference.

I am a PHP hack freak and just thought that it would be useful to show alternative ways of writing PHP. The more good programming that somebody is likely to see means that they are likely to produce even better programming once one fully understands the language. When I see better programming I pick up on it and it works in a circle.

If you take an old box and turn it into a web server, the last thing you want to be doing is writing unoptimised PHP programming as it will make an overall difference if you are to host a website visited by many people a day. I run an old and a new box and I often compare the differences between the two to see what is making a difference and what is not making a difference.

The only functions that do not make a difference to the speed of PHP are the language constructed functions that cannot be avoided in order to do what you want to do. Functions are there to make your job as a programmer a lot easier at the end of the day and do slow down the processing of PHP if heavily used to a point where they are looped tens of thousands of times (which I have yet to see in a program but still it might one day happen). I think we should all agree that if there is a more optimised way of doing something, it should at least be done in the correct way.