Data Types & Variables

Q1. Which of the following is a primitive data type in most languages?

1. A.List
2. B.Integer✓ Correct
3. C.Object
4. D.Array

Report an error in this question

Q2. What data type is used to store true or false values?

1. A.string
2. B.float✓ Correct
3. C.boolean
4. D.integer

Report an error in this question

Q3. What is a variable?

1. A.A fixed constant value in the program
2. B.A reusable block of executable code
3. C.A named storage location in memory✓ Correct
4. D.A control structure for iteration

Report an error in this question

Q4. What is the default value of an integer variable in Java?

1. A.1
2. B.-1
3. C.0✓ Correct
4. D.null

Report an error in this question

Q5. Which data type would you use to store a single letter?

1. A.String
2. B.double
3. C.boolean
4. D.char✓ Correct

Report an error in this question

Q6. What is the difference between float and double?

1. A.They are exactly the same data type
2. B.double has more precision than float✓ Correct
3. C.double is used for storing integers
4. D.float has more precision than double

Report an error in this question

Q7. What does declaring a variable mean?

1. A.Specifying its name and type✓ Correct
2. B.Assigning it an initial value
3. C.Printing its current value
4. D.Removing it from the memory

Report an error in this question

Q8. Which keyword is used to declare a constant in Java?

1. A.static
2. B.fixed
3. C.final✓ Correct
4. D.const

Report an error in this question

Q9. What is a string?

1. A.A boolean value
2. B.A single character
3. C.A sequence of characters✓ Correct
4. D.A numeric data type

Report an error in this question

Q10. What is type casting?

1. A.Removing a variable from program memory
2. B.Declaring a variable with a specific name
3. C.Converting a value from one type to another✓ Correct
4. D.Defining a brand new composite data type

Report an error in this question

Q11. What is the difference between implicit and explicit type casting?

1. A.Implicit casting always causes errors while explicit casting never does
2. B.Implicit is done automatically by the compiler; explicit is done manually✓ Correct
3. C.Explicit casting executes much faster than implicit casting at runtime
4. D.They are exactly the same type conversion process with no differences

Report an error in this question

Q12. What is the size of an int in Java?

1. A.32 bits✓ Correct
2. B.16 bits
3. C.8 bits
4. D.64 bits

Report an error in this question

Q13. What is the difference between value types and reference types?

1. A.Value types store data directly; reference types store a memory address✓ Correct
2. B.They are completely identical in behavior and memory representation
3. C.Value types are immutable and cannot be modified after creation
4. D.Reference types always execute faster than value types at all times

Report an error in this question

Q14. What happens when you assign a float value to an int variable without casting?

1. A.It works fine with no issues at all
2. B.Compilation error in strongly typed languages✓ Correct
3. C.The decimal part is automatically rounded up
4. D.The program crashes with a runtime exception

Report an error in this question

Q15. What is an enumeration (enum)?

1. A.A looping construct for iteration
2. B.A dynamically resizable array type
3. C.A function for string manipulation
4. D.A set of named constant values✓ Correct

Report an error in this question

Q16. What is the difference between signed and unsigned integers?

1. A.There is no meaningful difference between signed and unsigned types
2. B.Signed holds only positive values; unsigned holds negative values
3. C.They have different byte sizes in memory but the same value range
4. D.Signed holds negative and positive; unsigned holds non-negative only✓ Correct

Report an error in this question

Q17. What is a nullable type?

1. A.A type that is always null
2. B.A type with no default value
3. C.A type that cannot be null
4. D.A type that can hold a value or null✓ Correct

Report an error in this question

Q18. What is the result of integer overflow?

1. A.The value automatically becomes null
2. B.An exception is always thrown by runtime
3. C.The program always crashes immediately
4. D.The value wraps around in most languages✓ Correct

Report an error in this question

Q19. What is a union type in TypeScript?

1. A.A built-in type for numeric calculations
2. B.A type that can be one of several types✓ Correct
3. C.A type that combines properties of two types
4. D.A class that extends multiple parent classes

Report an error in this question

Q20. What is type aliasing?

1. A.Hiding a type from external modules
2. B.Renaming a declared variable in scope
3. C.Converting between different data types
4. D.Creating a new name for existing type✓ Correct

Report an error in this question

Q21. What is the IEEE 754 standard?

1. A.A specification for database schemas
2. B.A standard for security encryption
3. C.A protocol for computer networking
4. D.A standard for floating-point numbers✓ Correct

Report an error in this question

Q22. What is a phantom type?

1. A.A type providing compile-time safety without storing data✓ Correct
2. B.A type that has been deprecated from the language standard
3. C.A type reserved for representing ghost or phantom objects
4. D.A type that only exists at runtime and not at compile time

Report an error in this question

Q23. What is the difference between structural typing and nominal typing?

1. A.They are exactly the same concept with different names
2. B.Structural typing is only applicable to struct data types
3. C.Nominal typing is only applicable to numeric data types
4. D.Structural checks compatibility by shape; nominal by name✓ Correct

Report an error in this question

Q24. What is type erasure in Java generics?

1. A.Removing type information at the compile stage
2. B.Deleting all variables of a particular given type
3. C.Generic type info removed at runtime as raw types✓ Correct
4. D.Converting every type to Object at compile time

Report an error in this question

Q25. What is a dependent type?

1. A.A type that inherits from another
2. B.A type that depends on a library
3. C.A type that is defined by a value✓ Correct
4. D.A type that requires garbage collection

Report an error in this question

Q26. What is the bottom type in type theory?

1. A.A type with no values and subtype of every type✓ Correct
2. B.The null type representing an absence of a value
3. C.The base class that all other types inherit from
4. D.The standard integer type used for whole numbers

Report an error in this question

Q27. What is variance in type systems?

1. A.Random and unpredictable behavior in type inference
2. B.The size variation of different data types in memory
3. C.How subtyping of complex types relates to components✓ Correct
4. D.The total range of values a type can hold

Report an error in this question

Q28. What is an algebraic data type (ADT)?

1. A.An array type that exclusively stores numeric values
2. B.A data type designed for mathematical operations only
3. C.A type used for representing algebraic math expressions
4. D.A composite type combining sum and product operations✓ Correct

Report an error in this question

Q29. What is the unit type?

1. A.A type with exactly one possible value✓ Correct
2. B.A type used for measurement units
3. C.The integer constant value of one
4. D.A class with a single instance only

Report an error in this question

Q30. What is the purpose of type witnesses in advanced type systems?

1. A.To provide explicit proof of type relationships✓ Correct
2. B.To help debug complex type errors in code
3. C.To convert types dynamically during execution
4. D.To observe and log type changes at runtime

Report an error in this question