php

PHP Cheat Sheet

PHP tagsEmbed PHP in HTML

<?php
  echo "Hello, World!";
?>

Variables$ prefix, no type declaration

$name = "Mishu";
$age = 25;
$price = 19.99;

CommentsSingle and multi-line

// Single line
# Also single line
/* Multi-line */

Echo / PrintOutput to browser

echo "Hello $name!";
print("Hello World");

If-elseConditional execution

if ($x > 0) {
    echo "positive";
} else {
    echo "not positive";
}

ForeachIterate arrays

$items = ["a", "b", "c"];
foreach ($items as $item) {
    echo $item;
}

foreach ($arr as $key => $value) { }

For loopIteration

for ($i = 0; $i < 10; $i++) {
    echo $i;
}

ArrayIndexed and associative arrays

$nums = [1, 2, 3];
$user = [
    "name" => "Mishu",
    "age" => 25
];
echo $user["name"];

FunctionFunction definition

function greet($name, $greeting = "Hello") {
    return "$greeting, $name!";
}
echo greet("Mishu");

Array functionsUseful built-in functions

count($arr);
array_push($arr, $value);
array_merge($arr1, $arr2);
in_array($value, $arr);

GET / POSTAccess form data

// form.html: <input name="email">
$email = $_POST['email'];
$name = $_GET['name'];

SessionPersist data across pages

session_start();
$_SESSION['user_id'] = 1;
// On next page:
session_start();
$id = $_SESSION['user_id'];

MySQL connectionConnect to database

$conn = new mysqli($host, $user, $pass, $db);
$result = $conn->query("SELECT * FROM users");
while ($row = $result->fetch_assoc()) { }