Learn PHP Programming

<?php
// Writing to a file with fopen
$handle = fopen('log.txt', 'a'); // 'a' = append, 'w' = overwrite, 'r' = read
if ($handle === false) {
    die('Cannot open file for writing');
}

fwrite($handle, date('Y-m-d H:i:s') . " - User logged in\n");
fwrite($handle, date('Y-m-d H:i:s') . " - Page viewed\n");
fclose($handle); // Always close the handle!

// Reading a file line by line (memory efficient for large files)
$handle = fopen('log.txt', 'r');
if ($handle) {
    while (($line = fgets($handle)) !== false) {
        echo htmlspecialchars(trim($line)) . "<br>";
    }
    fclose($handle);
}

// Reading a specific number of bytes
$handle = fopen('data.bin', 'r');
$header = fread($handle, 1024); // Read first 1KB
fclose($handle);
?>

<?php
// Write entire content at once
$data = [
    'name' => 'My App',
    'version' => '2.1.0',
    'debug' => false
];
file_put_contents('config.json', json_encode($data, JSON_PRETTY_PRINT));

// Read entire file into a string
$config = json_decode(file_get_contents('config.json'), true);
echo $config['name']; // My App

// Append to a file (FILE_APPEND flag)
file_put_contents('visitors.log', date('c') . " - New visit\n", FILE_APPEND);

// Read file into an array (one element per line)
$lines = file('visitors.log', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
echo "Total visits: " . count($lines);

// Lock file during write to prevent race conditions
file_put_contents('counter.txt', $count, LOCK_EX);
?>

<?php
// Reading a CSV file line by line
$handle = fopen('products.csv', 'r');
if ($handle === false) {
    die('Cannot open CSV file');
}

// Read header row
$headers = fgetcsv($handle);
// ['id', 'name', 'price', 'stock']

// Read data rows
$products = [];
while (($row = fgetcsv($handle)) !== false) {
    // Combine headers with values for named keys
    $products[] = array_combine($headers, $row);
}
fclose($handle);

// Now you can work with structured data
foreach ($products as $product) {
    echo "{$product['name']}: \${$product['price']}\n";
}

// Writing CSV data
$handle = fopen('export.csv', 'w');
fputcsv($handle, ['Name', 'Email', 'Joined']); // Header
fputcsv($handle, ['Alice', 'alice@example.com', '2024-01-15']);
fputcsv($handle, ['Bob', 'bob@example.com', '2024-03-22']);
fclose($handle);
?>

<?php
$filepath = __DIR__ . '/data/config.json';

// Check existence and type
if (!file_exists($filepath)) {
    die("File not found: $filepath");
}

if (!is_file($filepath)) {
    die("Path is not a regular file");
}

// Check permissions before operations
if (!is_readable($filepath)) {
    die("File is not readable - check permissions");
}

if (!is_writable($filepath)) {
    die("File is not writable - check permissions");
}

// Get file information
echo "Size: " . filesize($filepath) . " bytes\n";
echo "Modified: " . date('Y-m-d H:i:s', filemtime($filepath)) . "\n";
echo "Type: " . mime_content_type($filepath) . "\n";

// Create directory if it doesn't exist
$uploadDir = __DIR__ . '/uploads';
if (!is_dir($uploadDir)) {
    mkdir($uploadDir, 0755, true); // recursive creation
}

// Safe file deletion
if (file_exists($filepath) && is_writable($filepath)) {
    unlink($filepath);
}
?>