C Declarations and Initializations Questions with Answers | Page 2

Understanding C Declarations and Initializations is fundamental for mastering C programming. These concepts are frequently covered in programming questions and answers for placement tests and technical interviews at companies like TCS, Infosys, and Wipro. Declarations define variables, while initializations assign values to them, both ensuring efficient memory and data handling in C. This guide provides C programming MCQs and practical examples that clarify variable scope, storage classes, and initialization rules. Ideal for both beginners and job seekers, it strengthens your coding logic and interview readiness with real-world examples and practice problems.

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Q11

What is the default value of an uninitialized local variable in C?

A 0
B NULL
C Garbage value
D 1

Answer: Option C

Explanation: Local variables are not automatically initialized and contain garbage values.

Q12

Which keyword is used to define a constant in C?

A constant
B define
C const
D fixed

Answer: Option C

Explanation: const keyword makes a variable read-only after initialization.

Q13

What is the size of int data type in C?

A 2 bytes
B 4 bytes
C 8 bytes
D Compiler dependent

Answer: Option D

Explanation: The size of int depends on the system architecture and compiler.

Q14

Which of the following is not a valid C identifier?

A my_var
B _var
C 2ndvar
D var2

Answer: Option C

Explanation: Identifiers cannot start with numbers or contain special characters.

Q15

What does the extern keyword do?

A Defines a new variable
B Declares a variable defined elsewhere
C Makes variable constant
D Allocates memory for variable

Answer: Option B

Explanation: extern declares a variable without defining it, indicating it is defined elsewhere.

Q16

Which storage class has the longest lifetime?

A auto
B register
C static
D extern

Answer: Option C

Explanation: static variables persist throughout the program execution.

Q17

What is the output of: printf("%d", sizeof(char));

Answer: Option A

Explanation: char always takes 1 byte in C regardless of the system.

Q18

Which of the following is a valid way to declare and initialize a string?

A char str[] = "Hello";
B char str = "Hello";
C string str = "Hello";
D char *str = 'H';

Answer: Option A

Explanation: Strings can be initialized using array syntax or pointer with string literal.

Q19

What is the value of an uninitialized global variable?

A 0
B Garbage value
C NULL
D Undefined

Answer: Option A

Explanation: Global variables are automatically initialized to zero by default.

Q20

Which of the following is a valid floating point declaration?

A float f = 3.14;
B float f = 3.14f;
C double d = 3.14;
D All of the above

Answer: Option D

Explanation: float and double are used for floating point numbers in C.

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