🧾 PHP Basics – Interview Questions

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🔹 1. Basic Questions (Very Important)

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

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

$name = "Aditya";

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

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

• String
• Integer
• Float
• Boolean
• Array
• Object

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5️⃣ Difference between echo and print?

echo	print
Faster	Slower
No return value	Returns 1
Can print multiple values	Only one

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🔹 2. Intermediate Questions

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

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

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

• == → compares value
• === → compares value + data type

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

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

Types:

• Arithmetic (+ - * / %)
• Comparison (== != > <)
• Logical (&& || !)

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

var_dump(10); // int(10)

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

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

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🔹 3. Tricky Questions (Asked in Interviews)

1️⃣1️⃣ What will be the output?

$x = 5;
echo $x++;

👉 Output: 5 (post-increment)

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1️⃣2️⃣ What will be the output?

$x = 5;
echo ++$x;

👉 Output: 6 (pre-increment)

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1️⃣3️⃣ Difference between single quotes and double quotes?

• ' ' → No variable parsing
• " " → Variables are parsed

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

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1️⃣4️⃣ Can we redeclare a constant?
👉 ❌ No

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

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🔹 4. Practical / Coding Questions

1️⃣6️⃣ Write a program to check even or odd

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

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1️⃣7️⃣ Swap two numbers

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

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1️⃣8️⃣ Find largest of two numbers

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

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🔥 Pro Interview Tips

• Always explain why, not just code
• Be clear on == vs === (very important)
• Know basic syntax + output prediction
• Practice small programs