🧾 PHP Basics – Interview Questions

🔹 1. Basic Questions (Very Important)

1️⃣ What is PHP?
👉 PHP (Hypertext Preprocessor) is a server-side scripting language used to build dynamic websites.

2️⃣ What are variables in PHP?
👉 Variables store data and start with $
Example:

$name = "Aditya";

3️⃣ Is PHP case-sensitive?
👉 Variables are case-sensitive ($name ≠ $Name)
👉 Keywords are NOT case-sensitive (echo = ECHO)

4️⃣ What are data types in PHP?
👉 Common types:

5️⃣ Difference between echo and print?

6️⃣ What is a constant in PHP?
👉 A constant is a fixed value that cannot be changed.

define("SITE", "SOA Technology");

7️⃣ What is the difference between == and ===?

10 == "10"   // true
10 === "10"  // false

8️⃣ What are operators in PHP?
👉 Symbols used to perform operations.

Types:

9️⃣ What is the use of var_dump()?
👉 It shows data type + value

var_dump(10); // int(10)

🔟 What are comments in PHP?
👉 Used to explain code

// single line
# single line/*
multi-line
*/

1️⃣1️⃣ What will be the output?

$x = 5;
echo $x++;

👉 Output: 5 (post-increment)

1️⃣2️⃣ What will be the output?

$x = 5;
echo ++$x;

👉 Output: 6 (pre-increment)

1️⃣3️⃣ Difference between single quotes and double quotes?

$name = "Aditya";echo 'Hello $name'; // Hello $name
echo "Hello $name"; // Hello Aditya

1️⃣4️⃣ Can we redeclare a constant?
👉 ❌ No

1️⃣5️⃣ What happens if you use an undefined variable?
👉 PHP shows a warning/notice

1️⃣6️⃣ Write a program to check even or odd

$num = 4;
if($num % 2 == 0){
  echo "Even";
} else {
  echo "Odd";
}

1️⃣7️⃣ Swap two numbers

$a = 5;
$b = 10;$a = $a + $b;
$b = $a - $b;
$a = $a - $b;

1️⃣8️⃣ Find largest of two numbers

$a = 10;
$b = 20;echo ($a > $b) ? $a : $b;