Top C Language Interview Questions & Answers (2026)
Beginner
40 Questions
Fresher Friendly
Updated Oct 2026
Search by question or keyword.
Follow Quizer
Interview Questions and Answers
Expand a question to view the answer and interview tip.
C is a general-purpose, procedural programming language developed by Dennis Ritchie at Bell Labs in 1972.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
C language was developed by Dennis Ritchie at Bell Laboratories in 1972.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
C is fast, portable, structured, supports pointers, dynamic memory allocation, and provides low-level access to memory.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
C is a procedural language, while C++ supports both procedural and object-oriented programming.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Data types define the type of data a variable can hold, such as int, float, char, double, and void.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A variable is a named location in memory used to store data.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Local variables are declared inside functions and have limited scope, while global variables are declared outside all functions and are accessible anywhere in the program.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A constant is a variable whose value cannot be changed during program execution.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
printf() is used to display output on the screen.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
scanf() is used to take input from the user.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A function is a block of code that performs a specific task and can be reused.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
main() is the entry point of every C program where execution starts.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Header files contain function declarations and macros. Example: stdio.h, stdlib.h, math.h.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Call by value passes a copy of the variable, while call by reference passes the address of the variable.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Pointers are variables that store the memory address of another variable.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A NULL pointer is a pointer that does not point to any valid memory location.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A dangling pointer points to a memory location that has been freed or deleted.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A structure is a user-defined data type in C that groups related variables of different data types.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
In structure, each member has its own memory, while in union, all members share the same memory space.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
An array is a collection of elements of the same data type stored in contiguous memory locations.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A string is a sequence of characters terminated by a null character (\0).
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Loops are used to execute a block of code repeatedly. Types: for, while, do-while.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
while checks the condition before execution, do-while checks after execution (executes at least once).
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Recursion is a process where a function calls itself.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A loop that never terminates because its condition always remains true.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
break exits the loop immediately, while continue skips the current iteration.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
A pointer to a pointer stores the address of another pointer variable.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Dynamic memory allocation allows programs to request memory during runtime using malloc(), calloc(), realloc(), and free().
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
malloc() dynamically allocates memory and returns a void pointer to it.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
calloc() allocates multiple blocks of memory and initializes them with zero.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
realloc() changes the size of previously allocated memory block.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
free() deallocates dynamically allocated memory to prevent memory leaks.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Preprocessor directives are commands that are processed before the program is compiled (e.g., #include, #define).
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Type casting is converting a variable from one data type to another.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
sizeof is used to determine the size (in bytes) of a data type or variable.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
== is a comparison operator, while = is an assignment operator.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
Storage classes define scope, lifetime, and visibility of variables: auto, static, extern, register.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
The static keyword preserves the value of a variable across function calls.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.
return sends control back from a function, while exit() terminates the entire program.
Interview Tip:
Keep your answer structured and support it
with practical examples wherever possible.