PSR-4 directory mapping in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the base namespace prefix for PSR-4 autoloading.

PHP

$prefix = "[1]\\";

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Aautoload

Bsrc

Cvendor

DApp

Attempts:

3 left

💡 Hint

Common Mistakes

Using folder names like 'src' or 'vendor' as namespace prefix.

Including backslashes in the prefix string.

The base namespace prefix is usually the project or application name, like App.

2fill in blank

medium

Complete the code to map the namespace prefix to the directory path in PSR-4.

PHP

$baseDir = __DIR__ . '/[1]/';

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Alib

Bbin

Csrc

Dapp

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'bin' or 'lib' which may not contain PHP classes.

Using absolute paths instead of relative paths.

The src directory is commonly used to store PHP source files for PSR-4 mapping.

3fill in blank

hard

Fix the error in the autoloader function to correctly replace namespace prefix with directory path.

PHP

if (strncmp($class, $prefix, [1]) !== 0) {
    return;
}

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Astrlen($prefix)

Bstrlen($class)

Cstrpos($class, $prefix)

Dstrlen($baseDir)

Attempts:

3 left

💡 Hint

Common Mistakes

Using length of directory path instead of prefix.

Using strpos which returns position, not length.

We compare the start of the class name with the length of the namespace prefix.

4fill in blank

hard

Fill both blanks to correctly build the file path from the class name.

PHP

$relativeClass = substr($class, [1]);
$file = $baseDir . str_replace([2], '/', $relativeClass) . '.php';

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Astrlen($prefix)

B'\\'

C'/'

Dstrlen($baseDir)

Attempts:

3 left

💡 Hint

Common Mistakes

Replacing forward slashes instead of backslashes.

Using length of base directory instead of prefix.

We remove the prefix length from the class name and replace backslashes with slashes for file paths.

5fill in blank

hard

Fill all three blanks to complete the PSR-4 autoloader registration code.

PHP

spl_autoload_register(function ($class) {
    $prefix = '[1]\\';
    $baseDir = __DIR__ . '/[2]/';
    if (strncmp($class, $prefix, [3]) !== 0) {
        return;
    }
});

Drag options to blanks, or click blank then click option'

AApp

Bsrc

Cstrlen($prefix)

Dlib

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong directory names.

Not using the length of prefix in strncmp.

This code registers an autoloader that maps the App\ namespace to the src directory and checks the prefix length correctly.