PHP 5 - The scope of a variable includes files without classes or functions

Question

I have read many, many threads on this and still cannot wrap myself around.

Here is my main problem:

header.php includes a file called navigation.php . Within navigation.php , $previous and $next defined. Using the echo commands, I confirmed that they matter.

Next, header.php contains a file called backnext.php . I need backnext.php to know the values ​​of $previous and $next . If I declare them as global at the top of backnext.php , I get no errors, but the echo instructions show that they are empty. If I do not, I get an undefined variable error.

Where exactly do I need to declare them as global so that backnext.php can read their values ​​correctly?

None of these files use functions or classes.

Answer 1

If none of these files has functions or classes, then $prev and $next are in the global scope and should be displayed by all of your included files, and you do not need to use the global .

It looks like the order of your inclusions may be a little wrong.

Update:

If I understood correctly, you have something like this:

header.php:

 <?php echo "In header.php\n"; require_once("navigation.php"); require_once("backnext.php"); echo "Also seen in header.php:\n"; echo "prev=$prev\n"; echo "next=$next\n"; ?> 

navigation.php:

 <?php echo "In navigation.php\n"; $prev = "Hello World#1"; $next = "Hello World#2"; echo "Exiting navigation.php\n"; ?> 

backnext.php:

 <?php echo "In backnext.php\n"; echo "prev=$prev\n"; echo "next=$next\n"; echo "Exiting backnext.php\n"; ?> 

If I run this, I get:

  In header.php
 In navigation.php
 Exiting navigation.php
 In backnext.php
 prev = Hello World # 1
 next = Hello World # 2
 Exiting backnext.php
 Also seen in header.ph
 prev = Hello World # 1
 next = Hello World # 2

backnext.php can see both $prev and $next .

Answer 2

I think that you probably have a logical error somewhere where the contents of the variables get destroyed, or as @Kev noted, the execution thread is wrong. Here are some test codes:

File: test.php

 <?php $test = "Hi!"; require_once 'test2.php'; require_once 'test3.php'; ?> 

File: test2.php

 <?php echo("Test 2: " . $test . "<br/>"); ?> 

File: test3.php

 <?php echo("Test 3: " . $test . "<br/>"); ?> 

This leads to the output:

 Test 2: Hi! Test 3: Hi! 

Which proves that the variable $test in the global scope, and should be available for any script after it is defined.

PS - Don't rely on SO users to provide your reference material. Go straight to the source: Scope Variable - PHP Manual The first paragraph on this page reads:

The scope of a variable is the context within which it is defined. For most PHP variables, they only have a single scope. This is the only area included and required files, as well.

Edit

Try this in header.php and see what happens:

 <?php include 'navigation.php'; echo($previous . " ; " . $next . "<br/>"); include 'backnext.php'; echo($previous . " ; " . $next . "<br/>"); ?> 

If you do not get the same result both times, then there is a problem in backnext.php where the variables get wiped. If it produces the same output, then move the echoes inside backnext.php at the highest and lowest level. Logically, they don’t actually move them, but you can move them closer and closer until you find where the problem is.