MCQs on Variables and Data Types | PHP Basics

Explore your understanding of PHP fundamentals with these multiple-choice questions, crafted to reinforce core concepts like variable declaration, data types, type casting, and constants. Perfect for beginners in PHP!

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Variables and Data Types

Declaring Variables

1. Which of the following is the correct way to declare a variable in PHP?
   • a) var myVariable = "Hello";
   • b) $myVariable = "Hello";
   • c) myVariable := "Hello";
   • d) int myVariable = "Hello";
2. Which symbol is used to prefix a variable name in PHP?
   • a) %
   • b) #
   • c) @
   • d) $
3. Which of the following statements about variables in PHP is correct?
   • a) Variable names can start with a number.
   • b) Variable names cannot contain special characters.
   • c) PHP variable names are case-insensitive.
   • d) PHP variable names must start with a letter or underscore.
4. Which of the following is a valid PHP variable name?
   • a) $123name
   • b) $name@
   • c) $name
   • d) $-name

Data Types in PHP (String, Integer, Float, Boolean, Array, Object, NULL)

5. Which data type is NOT a primitive type in PHP?
   • a) Boolean
   • b) Array
   • c) Integer
   • d) Object
6. What is the data type of a variable $x = 5.6; in PHP?
   • a) Integer
   • b) Boolean
   • c) Float
   • d) String
7. What will be the data type of $x = true; in PHP?
   • a) String
   • b) Integer
   • c) Boolean
   • d) Float
8. Which of the following statements about PHP arrays is correct?
   • a) Arrays in PHP can only contain integers.
   • b) Arrays in PHP can store values of different data types.
   • c) Arrays in PHP can only store objects.
   • d) Arrays in PHP are limited to a fixed size.
9. How do you define a NULL variable in PHP?
   • a) $var = 0;
   • b) $var = "";
   • c) $var = NULL;
   • d) $var = "null";
10. Which data type does PHP automatically assign when a variable is assigned a textual value?

• a) Boolean
• b) Array
• c) String
• d) Integer

11. If $x = "5" + 5;, what will be the resulting data type of $x?

• a) Integer
• b) String
• c) Float
• d) Boolean

12. Which of the following data types can store decimal values?

• a) Integer
• b) Float
• c) Boolean
• d) Array

13. How would you declare an empty object in PHP?

• a) $obj = [];
• b) $obj = new object();
• c) $obj = new stdClass();
• d) $obj = {};

Type Casting

14. Which of the following correctly converts an integer to a float in PHP?

• a) (int)$variable
• b) (float)$variable
• c) float($variable)
• d) (integer)$variable

15. If $var = "5.6", which of the following will convert $var to an integer?

• a) (string)$var
• b) (int)$var
• c) (boolean)$var
• d) (float)$var

16. How can you convert a variable $num of type float to an integer in PHP?

• a) $num = (float)$num;
• b) $num = (int)$num;
• c) $num = (string)$num;
• d) $num = boolval($num);

17. In PHP, which of the following is NOT a way to type cast a variable?

• a) (int)$var
• b) (boolean)$var
• c) (array)$var
• d) (char)$var

18. What will be the result of the following PHP code: $val = (string)100;?

• a) $val becomes an integer.
• b) $val becomes a float.
• c) $val becomes a string.
• d) $val becomes an array.

19. If $data = (bool)"false";, what will be the value of $data?

• a) false
• b) true
• c) 0
• d) 1

20. Which function is used to get the data type of a variable in PHP?

• a) type()
• b) gettype()
• c) datatype()
• d) vartype()

Constants in PHP

21. How do you define a constant in PHP?

• a) $CONSTANT = "Value";
• b) define("CONSTANT", "Value");
• c) constant "CONSTANT" = "Value";
• d) CONSTANT = "Value";

22. Which of the following is TRUE about PHP constants?

• a) They can be redefined.
• b) They are case-sensitive by default.
• c) They cannot be used inside functions.
• d) They must start with a $ symbol.

23. Which function can be used to check if a constant is already defined?

• a) is_constant()
• b) constant_exists()
• c) defined()
• d) isset()

24. Which keyword is used in PHP to define a constant?

• a) var
• b) define
• c) constant
• d) const

25. Once defined, how can you access a constant named MAX_VALUE in PHP?

• a) $MAX_VALUE
• b) MAX_VALUE
• c) @MAX_VALUE
• d) #MAX_VALUE

26. Which of the following best describes a constant in PHP?

• a) A variable that changes value frequently.
• b) A value that cannot be changed once set.
• c) A function parameter.
• d) A temporary variable.

27. How do you define a case-insensitive constant in PHP?

• a) define("constant_name", "value", true);
• b) define("constant_name", "value", false);
• c) const constant_name = "value";
• d) define_constant("constant_name", "value", true);

28. Which of the following cannot be assigned to a constant in PHP?

• a) Integer
• b) Float
• c) Array
• d) String

29. How do constants differ from variables in PHP?

• a) Constants require the $ prefix.
• b) Constants can be changed during runtime.
• c) Constants do not need the $ prefix.
• d) Constants are only accessible within functions.

30. Which of the following is NOT true about constants in PHP?

• a) They can be defined using the define() function.
• b) They are automatically global across scripts.
• c) They start with a $ symbol.
• d) They cannot be redefined once set.

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Answer Key

Qno	Answer
1	b) $myVariable = "Hello";
2	d) $
3	d) PHP variable names must start with a letter or underscore.
4	c) $name
5	d) Object
6	c) Float
7	c) Boolean
8	b) Arrays in PHP can store values of different data types.
9	c) $var = NULL;
10	c) String
11	a) Integer
12	b) Float
13	c) $obj = new stdClass();
14	b) (float)$variable
15	b) (int)$var
16	b) $num = (int)$num;
17	d) (char)$var
18	c) $val becomes a string.
19	b) true
20	b) gettype()
21	b) define("CONSTANT", "Value");
22	b) They are case-sensitive by default.
23	c) defined()
24	d) const
25	b) MAX_VALUE
26	b) A value that cannot be