Top 100 C Interview Questions and Answers

A static variable in C is a variable that retains its value between function calls.

• Static variables are declared using the 'static' keyword.

• They are initialized only once, at the start of the program.

• Their value persists even after the function call ...read more

Yes, it is possible to declare a structure 'a' that contains a structure 'b' and 'b' in turn contains 'a'.

• To achieve this, we can use forward declaration of one of the structures.

• By using a pointer or reference to the other structure inside the first...read more

Criteria for C program include syntax correctness, logical flow, efficiency, and readability.

• Correct syntax and logical flow are essential for program functionality

• Efficiency is important for performance optimization

• Readability ensures ease of mainte...read more

The difference is that 'int arr[5]' creates an array on the stack, while 'malloc(5*sizeof(int))' allocates memory on the heap.

• int arr[5] creates an array of 5 integers on the stack, which is a fixed-size memory allocation.

• malloc(5*sizeof(int)) dynami...read more

It is not possible to write a C program in Java as they are two different programming languages.

• C and Java are different programming languages with different syntax and features.

• C programs are written using C syntax and compiled with a C compiler.

• Jav...read more

The maximum memory that can be allocated with malloc() depends on the system's available memory and the size of the largest contiguous block of memory.

• The maximum memory that can be allocated is limited by the system's available memory.

• The size of th...read more

Storage classes in C define the scope and lifetime of variables.

• auto: default storage class for local variables

• register: stores variables in CPU registers for faster access

• static: retains value between function calls

• extern: used to access global vari...read more

C is a programming language used to create software and operating systems.

• C is a low-level language that allows direct access to computer hardware.

• It is used to create efficient and fast programs.

• C is the foundation for many other programming languag...read more

Latest embedded C programming includes features like dynamic memory allocation, multi-threading, and object-oriented programming.

• Dynamic memory allocation allows for more efficient use of memory

• Multi-threading enables concurrent execution of multiple...read more

Use the sizeof operator on a variable of type int to get its size.

• Use sizeof operator on a variable of type int

• Size of int is typically 4 bytes

• Size may vary depending on the system architecture

A program in C is a set of instructions written in the C programming language to perform a specific task.

• C programs are written using a combination of variables, data types, control structures, and functions.

• They are compiled into machine code and ex...read more

Write a small C code

• Use the main function as the entry point of the program

• Declare variables and assign values as needed

• Use loops and conditionals to control the flow of the program

• Utilize arrays and strings to store and manipulate data

• Include necess...read more

Preprocessor in C is a tool that processes source code before compilation.

• It performs macro substitution

• It includes header files

• It conditionally compiles code

• It defines constants and symbols

• It removes comments

• Examples of preprocessor directives are #...read more

C language is a high-level programming language used for system programming and developing applications.

• C is a compiled language

• It is used for developing operating systems, device drivers, and other system software

• C is also used for developing deskto...read more

Dynamic mode file is a file that is created and modified during runtime.

• Dynamic mode files are created and modified during runtime

• They are not stored on disk, but in memory

• Examples include temporary files and buffers

A null pointer points to nothing while a void pointer can point to any data type.

• A null pointer is a pointer that has been explicitly set to a null value.

• A void pointer is a pointer that has no type associated with it.

• A null pointer is a subtype of a...read more

Control statements are used to control the flow of execution in a program.

• There are three types of control statements in C: decision-making statements, loop statements, and jump statements.

• Decision-making statements include if-else and switch stateme...read more

Structure is a user-defined data type that groups related data members, while union is a data type that allows storing different data types in the same memory location.

• Structures are used to group related data members of different data types, while u...read more

A function pointer is a variable that stores the address of a function. Volatile type is used to declare variables that can be modified by external factors.

• Function pointers are used to pass functions as arguments to other functions.

• Volatile type is ...read more

Function pointers in C are used to store the address of functions, allowing for dynamic function calls and callbacks.

• Function pointers can be used to implement callbacks in event-driven programming.

• They can be used to switch between different functio...read more

Memory allocation in C is done using functions like malloc, calloc, realloc and free.

• malloc function is used to allocate a block of memory of specified size

• calloc function is used to allocate a block of memory and initialize it to zero

• realloc functio...read more

I would rate my C coding skills as 4 out of 5.

• Proficient in writing efficient and clean C code

• Experience in developing complex algorithms and data structures

• Familiar with low-level programming and memory management

• Able to debug and optimize code for ...read more

To invoke an XML file using LibXML, use the xmlReadFile() function.

• Include the libxml/parser.h header file.

• Use the xmlReadFile() function to read the XML file and create a xmlDocPtr object.

• Use the xmlDocGetRootElement() function to get the root eleme...read more

C language is a popular programming language known for its efficiency and low-level programming capabilities.

• C language is a general-purpose programming language.

• It was developed by Dennis Ritchie at Bell Labs in the early 1970s.

• C language is widely ...read more

Implement the strstr() function in C to find the index of the first occurrence of one string in another.

• Iterate through the main string and check if the substring matches at each position.

• Return the index if a match is found, else return -1.

• Handle ed...read more

Calculate size of variable without library function

• Use the sizeof operator to calculate the size of a variable

• Multiply the size by the number of elements if it's an array

• Size of a struct is the sum of sizes of its members

• Size of a union is the size o...read more

API call in C

• Include the necessary header files

• Create a URL string with the required parameters

• Use the curl library to make the API call

• Handle the response data appropriately