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PHP

Ammu Nair
Ammu Nair
9,100 Points
Posted by Ammu Nair
Ammu Nair
9,100 Points

Sort - Clarification required in stmt combining two if's.

Hi, I need some help in understanding the stmt where the 2 if stmts are combined. They were given separately so that the catalogs could be viewed as per category. If it is combined using an OR, how will the catalogs be displayed as per category ? In fact, if they are combined using an OR, there isnt any need of an IF stmt at all, as it will always be true. Please explain.

Simon Coates
Simon Coates
28,694 Points
Simon Coates
Simon Coates
28,694 Points

can you post the code, or a link to the video that this is in reference to?

1 Answer

Simon Coates
Simon Coates
28,694 Points
Simon Coates
Simon Coates
28,694 Points 
if ($category == null OR strtolower($category) == strtolower($item["category"])) {

if category is not null and the categories doesn't match, it will not be true. you can past conditions together using an OR when the same action occurs if either (or both) conditions are met. It is possible to accidentally create a effective tautology (or a contradiction), but here there is another case - !($category == null OR strtolower($category) == strtolower($item["category"])) evaluates to ($category != null AND strtolower($category) != strtolower($item["category"])). If there are two possible outcomes, an if statement still makes sense.

Ammu Nair
Ammu Nair
9,100 Points
Ammu Nair
Ammu Nair
9,100 Points

Hi, If the category is 'books', we want only the items with category = 'books' to be displayed. Could you please explain how using this code, the items with only category = 'books' are displayed.

Simon Coates
Simon Coates
28,694 Points
Simon Coates
Simon Coates
28,694 Points

It tests category == null. this is not true so it looks at the next part. The category 'books' equals the category on some items. False OR true - is true.

You can demo the test:

<?php
 $item = [    "category"=>"Books"     ];
 $category = 'books';

 if ($category == null OR strtolower($category) == strtolower($item["category"])) {
   echo "a";
 }

 $category = 'null';
 if ($category == null OR strtolower($category) == strtolower($item["category"])) {
   echo "b";
 }

 $category = 'Movies';
 if ($category == null OR strtolower($category) == strtolower($item["category"])) {
   echo "c";
 }
?>

Only "a" is displayed