Educational

Category: PHP

  • sessions and cookies in PHP?

    • Sessions: Store data on the server, unique for each user.
    • Cookies: Store data on the client/browser.

  • include and require?

    • include → gives a warning if file missing, script continues.
    • require → gives a fatal error and stops execution.

  • superglobals in PHP?

    Predefined global arrays available anywhere in PHP:

    • $_GET – data from URL query string
    • $_POST – data from forms
    • $_SESSION – session variables
    • $_COOKIE – cookies
    • $_SERVER – server/environment info
    • $_FILES – file uploads
    • $_REQUEST – combines GET + POST + COOKIE

  • == and === in PHP?

    • == checks for value equality (ignores type).
    • === checks for value and type equality.
    var_dump(5 == "5");   // true
var_dump(5 === "5");  // false

  • What are PHP data types?

    • String
    • Integer
    • Float (double)
    • Boolean
    • Array
    • Object
    • NULL

  • echo and print in PHP?

    • echo can output multiple strings, and is slightly faster.
    • print can only output one string, and always returns 1.
    echo "Hello ", "World";   // works
print "Hello World";      // works

  • What is PHP and why is it used?

    • PHP stands for Hypertext Preprocessor.
    • It is a server-side scripting language used to create dynamic web applications.
    • It can connect with databases, handle forms, manage sessions/cookies, etc.

  • File Handling

    <?php
$file = fopen("example.txt", "w");
fwrite($file, "Hello File Handling!");
fclose($file);

$file = fopen("example.txt", "r");
echo fread($file, filesize("example.txt"));
fclose($file);
?>

    Explanation:

    • "w" → write mode (creates/overwrites file).
    • "r" → read mode.
    • fwrite writes text into file, fread reads it.

  • String Functions

    <?php
$text = " Hello PHP! ";

echo strlen($text);    // 11
echo strtolower($text); // hello php!
echo strtoupper($text); // HELLO PHP!
echo trim($text);       // removes extra spaces
echo str_replace("PHP", "World", $text); // Hello World!
?>

    Explanation:
    PHP has many string functions for modifying and formatting text.

  • Switch Case Example

    <?php
$day = "Monday";

switch ($day) {

    case "Monday":
    echo "Start of the week!";
    break;
case "Friday":
    echo "Weekend is near!";
    break;
default:
    echo "Just another day.";
    }
?>

    Explanation:

    • switch is an alternative to multiple if-else statements.
    • If $day = "Monday", output will be Start of the week!