Top C Programming Interview Questions with answers

Any corporation or organization’s selection procedure must include interview questions. One must be completely prepared for the interview questions before facing the interviewer. You will examine the most often asked C++ interview questions that one should be aware of in this tutorial on C++ interview questions.

What is C programming?

C is one of the oldest programming languages, developed in 1972 by Dennis Ritchie. It is a high-level, general-purpose, and structured programming language extensively used in system applications, desktop applications, operating systems, and IoT applications. C is known for its simplicity, flexibility, and efficiency, making it suitable for a wide range of tasks.

Why is C dubbed as the mother language?

C is referred to as the mother language because most JVMs, compilers, and kernels are written in C. Proficiency in C facilitates learning other programming languages.

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Who is the founder of the C language, and when was it developed?

C was developed by Dennis M. Ritchie in 1972 at Bell Laboratories of AT&T.

What are the key features of the C programming language?

Major features of C include:

• Machine independence
• Mid-level programming language
• Memory management
• Structured programming language
• Simplicity and efficiency
• Rich function libraries
• Case sensitivity

Name some different storage class specifiers in C.

Storage class specifiers represent how variables are stored in memory. The four storage classes in C are:

• Auto
• Register
• Extern
• Static

What are the data types supported in the C programming language?

C supports various data types:

• Built-in data types: int, char, double, float, and void
• Derived data types: array, pointers, and references
• User-defined data types: union, structure, and enumeration

Explain the scope and lifetime of a variable in C.

The scope and lifetime of a variable determine where and for how long it exists in a program. Scope defines the section of the code where a variable is accessible, while lifetime refers to the variable’s existence before it is destroyed.

What is a pointer in C?

Pointers in C are variables that store memory addresses of other variables. They dynamically allocate memory during runtime and can be of different data types such as int, char, float, and double.

Define a null pointer.

A null pointer represents an empty location in a computer’s memory. It is used for various purposes such as:

• Assigning a pointer variable to a memory location with no assigned memory
• Error handling in pointer-related code
• Passing a null pointer when a valid memory address is not needed

What is the use of functions in C?

Functions are essential building blocks in C programming. They enable:

• Code reusability
• Modularity and better code organization
• Easy tracking and debugging of C programs

What are header files in C?

Header files contain C function declarations and macro definitions shared between source files. They are included using the #include directive and have a .h extension.

What is the purpose of the extern storage specifier?

The extern storage specifier allows you to declare a variable without instantiating it. Its value can be assigned in a different block and changed across different blocks. Extern variables are global and can be accessed from anywhere in the code.

Explain the difference between rvalue and lvalue in C.

In C, rvalue refers to objects appearing on the right side, while lvalue refers to expressions appearing on the left side of an assignment operation.

Can a program be compiled without the main() function?

Yes, a C program can be compiled without the main() function, but it will not execute without it.

Define a stack.

A stack is a data structure used to store data in a particular order in which operations are performed. It follows two order types: LIFO (Last In, First Out) and FIFO (First In, First Out). Basic stack operations include push, pop, peek (or top), and is Empty.

When is the arrow operator used?

The arrow operator (->) is used to access elements in a structure and union. It is used with a pointer variable and is formed by combining the minus sign (-) with the greater than symbol (>).

What is a token in C?

A token is the smallest individual unit in a C program. Tokens in C are classified as:

• Keywords
• Constants
• Identifiers
• Strings
• Operators
• Special symbols

Name the keyword used for unconditional branching.

The keyword used for unconditional branching is the go-to statement.

What is the use of the comma operator in C?

The comma operator is used to separate two or more expressions in a C program.

What is the length of an identifier in C?

The length of an identifier in C is 31 characters.

What is typecasting in C?

Typecasting in C is a way to convert a variable from one data type to another. There are two types of typecasting in C: implicit conversion and explicit conversion.

What is FIFO?

FIFO stands for First In, First Out. It is a cost flow assumption used to remove costs from the inventory account.

What is the use of the built-in stricmp() function?

The built-in stricmp() function compares two strings and returns an integer.

What is the function used to close a file stream?

The function used to close a file stream is fclose().

What is a union?

A union is a user-defined data type that allows you to store multiple types of data in a single memory location. However, only one member of the union can hold a value at a time. It holds the memory of the largest member and not the sum of the memory of all members.

What happens if a header file is included twice?

If a header file is included twice, the compiler processes its contents twice, resulting in an error. To prevent this, a header file can be guarded using preprocessor directives (#ifndef, #define, #endif).

Can a C program compile without the main() function?

Yes, a C program can be compiled without the main() function, but it will not execute without it.

What is a memory leak in C?

A memory leak occurs when programmers allocate memory on the heap but forget to deallocate it, resulting in memory that is no longer needed but remains undeleted. This can lead to additional memory usage and affect the program’s performance.

What do while(0) and while(1) mean?

while(0) is a loop that never executes its body, as the loop condition is always false. On the other hand, while(1) creates an infinite loop that continues until it is explicitly exited.

Explain the difference between prefix increment and postfix increment.

In prefix increment (++a), the value of the variable is incremented before the current value is used in the expression. In postfix increment (a++), the value of the variable is incremented after its current value is used in the expression.

What is the difference between a null pointer and a void pointer?

A null pointer is one that does not point to any valid location in memory, and its value is set to NULL. On the other hand, a void pointer is a generic pointer that can point to any data type but does not have any associated data type

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