About require (Strtolower ($object). '. class.php ') Related issues

About require (Strtolower ($object). The question of '. class.php ')
Code require (Strtolower ($object). '. class.php '); Run the following error message appears:

Fatal Error:require (): Failed opening required ' pscws3.class.php ' (include_path= '.; C:\php\pear ') in D:\php\wamp\www\scws002\demo.php on line 208
I changed it to require ". class.php"; it's working. But here I don't understand why it's important to have a case-and-write conversion. What is the correct wording?


------Solution--------------------
Prevent the size to write wrong ... Causes the path to be incorrect, forcing is converted to lowercase. What else could it do?

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This is not the point, I want to know that when referencing the file, the above code uses the Strtolower () function, I do not know what this can bring benefits

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