PHP File Handling

<?php
$file = "data.txt";

// Write (overwrites existing content)
file_put_contents($file, "Hello, World!\n");

// Append to file
file_put_contents($file, "Second line\n", FILE_APPEND);

// Read entire file as string
$content = file_get_contents($file);
echo $content;

// Read file into array (one element per line)
$lines = file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
foreach ($lines as $line) {
    echo $line . "\n";
}

// fopen / fwrite / fclose — low-level control
$handle = fopen("log.txt", "a"); // 'a' = append mode
if ($handle) {
    fwrite($handle, date("Y-m-d H:i:s") . " - Event logged\n");
    fclose($handle);
}
?>

<?php
$file = "data.txt";

// Check existence
if (file_exists($file)) {
    echo "File exists\n";
    echo "Size: " . filesize($file) . " bytes\n";
    echo "Is file: " . (is_file($file) ? "yes" : "no") . "\n";
    echo "Is dir: "  . (is_dir($file)  ? "yes" : "no") . "\n";
    echo "Readable: " . (is_readable($file) ? "yes" : "no") . "\n";
}

// Rename / move
rename("old.txt", "new.txt");

// Delete
if (file_exists("temp.txt")) {
    unlink("temp.txt");
}

// Directory operations
mkdir("uploads", 0755, true);  // create recursively
$files = scandir("uploads");   // list directory contents
foreach ($files as $f) {
    if ($f !== "." && $f !== "..") echo $f . "\n";
}
rmdir("empty_folder"); // remove empty directory
?>

<?php
// fopen() mode reference:
// "r"  — read only, pointer at start
// "r+" — read/write, pointer at start
// "w"  — write only, truncate or create
// "w+" — read/write, truncate or create
// "a"  — write only, pointer at end (append)
// "a+" — read/write, pointer at end
// "x"  — create and write, fails if exists
// "x+" — create and read/write, fails if exists

// Reading line by line
$handle = fopen("data.txt", "r");
if ($handle) {
    while (($line = fgets($handle)) !== false) {
        echo trim($line) . "\n";
    }
    fclose($handle);
}

// Reading CSV
$csv = fopen("users.csv", "r");
while (($row = fgetcsv($csv)) !== false) {
    echo implode(", ", $row) . "\n";
}
fclose($csv);
?>