What best practices should be followed when concatenating variables to create file paths in PHP?

When concatenating variables to create file paths in PHP, it is important to use the correct directory separator to ensure compatibility across different operating systems. The PHP constant DIRECTORY_SEPARATOR can be used to dynamically insert the correct separator based on the current operating system. Additionally, it is recommended to sanitize and validate user input to prevent directory traversal attacks. 

// Example of concatenating variables to create a file path using DIRECTORY_SEPARATOR
$directory = 'uploads';
$filename = 'example.txt';

// Concatenate variables with DIRECTORY_SEPARATOR to create a file path
$file_path = $directory . DIRECTORY_SEPARATOR . $filename;

// Output the file path
echo $file_path;

Keywords

concatenation file paths variables PHP best practices

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