Advance C Programming Interview Questions

Advance C Programming Interview Questions | Freshers & Experienced

  • Pradeep
  • 06th Dec, 2021

About Advance C Programming

Despite the oldest language, C never be replaced by any modern language, as it is the core of every machine. One can say that it is the base for any programing language. It is a simple and flexible machine-independent language which is used in various applications. C language was first invented to design the operating system UNIX, but due to its popularity, it is widely used as a system programming language.

If you are a beginner in programming, then C will be a good choice to start with. If you are still confused, then check our online interview questions related to C and clear your doubts.

Key Features of Advance C Programming

Below are few major features of Advance C Programming

Procedural Language

Fast and Efficient


Statically Type

General-Purpose Language

Rich set of built in Operators

Libraries with rich Functions

Middle-Level Language

Practice Advance C Programming Interview Questions

Q1. What is difference between Stack and Queue?

A stack comprises of an impressionistic data type, constituted by physical stacks of units where addition and removal occur at the very same end. It is built on the LIFO principle that indicates last-in-first-out. The object might be figured up solely at a moment, or the object may be deleted which has been lastly added. A single pointer is utilized in the stack. Push and Pop, adds and removes newly added entities from a stack respectively. Stacks are envisioned as a vertical body. Like a pack of plates at a party.

However, a queue is opened at either end. It is built on the FIFO principle, which indicates first-in-first-out. Here you may only remove the first added entity. Duplet pointers are utilized here. Enqueue, dequeue add and removes entities to the stern and from the forepart of a queue respectively. Queues are horizontal. E.g. waiting for a mode of transport.

Q2. What is c preprocessor?

CPP or C pre-processor is a macro pre-processor for the C++ and C programming languages. A pre-processor offers the facility to include macro expansions, header files, line control, and conditional compilation. C preprocessor is simply a text replacing tool, which guides the compiler to perform the needed pre-processing earlier than the real compilation. It extends the horizon of a programming condition. Hence, its commands change the actual code in accordance with the operating condition and sum up the code which might be needed to library functions by calls. It is easily maintained, portable and enhances the legibility of C programming.

C Preprocessor

Q3. What is hashing in C language?

Hashing is basically designed to solve the problem of needing to efficiently find or store an item in a collection. In Hashing the data is passed through a specific formula in order to produce a result, known as a hash. A hash is usually a string of characters and the hashes generated by a formula are always the same length, regardless of how much data you feed into it.

Q4. Explain huge pointer in c?

In C, a Huge pointer is similar to a far pointer in terms of size as it has the same size of 32-bit as that of a far pointer, but it can also access bits that are located outside the sector. It can point or access whole the residence memory of RAM that means it accesses all of the 16 segments such that it is used to bit address up to 16 bits in a given section of the computer memory.

Q5. What is null pointer in c?

In C, a NULL pointer is basically used to indicate that the pointer doesn’t point to a valid location. Ideally, we should initialize pointers as NULL if we don’t know their value at the time of declaration. A null pointer is a pointer that points nothing that means it is a variable with the value assigned as zero or having an address pointing to nothing.

Q6. What is the use of pointers?

In C, Pointers save memory space is used to store and manage the addresses of dynamically allocated blocks of memory. A Pointer in C is used to allocate memory dynamically i.e. at run time. The pointer variable might be belonging to any of the data types such as int, float, char, double, short, etc.

Q7. What is assert() in C?

Assert in C is a macro that checks the specific locations at runtime. Assert() is useful for debugging a program while it is still under execution. To use assert, "assert.h" must be included in the header file program. It is a statement to test the assumptions made by a programmer. Assert also checks if the pointer the malloc() return is null or not.

Assertions are run to check the impossible situations that are logically unfeasible to exist. They are completely disabled during runtime.

Q8. How can we convert integers to binary in C?

You can convert integers to binary in C by following the mentioned steps:

  • Divide the number by 2 through % i.e. modulus operator and store the remainder in an array.
  • Divide the number by 2 through / i.e. division operator
  • Repeat step 2 until the number is greater than 0.

Q9. Are pointers are faster than arrays?Explain?

No, pointers are not faster than arrays. As array access is faster if the array is allocated in the local stack scope or in static memory. Memory allocation of the array is also continuous thus making it faster than pointers as in pointers the memory allocation might or might not be continuous.

Q10. How can we clear the screen in C?

We can clear the screen in C by using the clear screen command i.e. clrscr(). Clrscr() is predefined function in conio. h therefore by using this function we can clear the data from the console.

Q11. How to read single character in C?

To read a single character in C, you can use simply the scanf command. Syntax - scanf("%c", &ch) where ch is the variable to store the character. It reads one character given in the form of input by the user.

Q12. What is "Hungarian Notation"?

Hungarian Notation happens to be an identifier denominating accord in computer coding or programming, where the denomination of a function or variable specifies its kind or intention and in imperceptible dialects its nature. It was devised to be dialect independent, eventually, it is utilized in the BCPL programming language. As BCPL, has negligible data types excluding the machine command, there is not a thing in the dialect that can aid programmer recollect variables’ types. Thus, Hungarian Notation's objective solves the problem by offering a programmer with the plain and direct command of every variable's data kind.

To simply put, Hungarian Notation being an anonym convention permits the programmer to control the variable’s types only by a glimpse at its denomination.

Q13. What is Dangling pointer?

Dangling Pointers emerges in the course of object destruction. When a target's incoming reference has been deallocated or deleted sans enhancing the pointer's evaluation, consequently the pointer nonetheless points towards the memory site of the obliterated memory. It can be also said that any pointer which contains no valid address or denotes a wrecked object is known as the Dangling Pointer.

Generally, Dangling Pointers are the outcome of use-after-delete, although it may also develop from yielding a stacked object’s address and utilizing it later when the stack structure has expired.

Q14. What is use of sizeof in C?

Sizeof is a much-used operator in the C that can be used to compute the size of its operand. It generates the storage size of an expression or a data type, measured in the number of char-sized units. It can be used as sizeof() function and your input is written inside the bracket. For ex- sizeof (char).

Q15. How to find memory leak in C?

The steps to find a memory leak in C are as follows:

  • Now to test memory leak, just add the leak_detector_c. h file to the test file and add one line to the start of the main function. 
  • Now compile the code and run the program: Copy Code.

Q16. What is size of void pointer?

The size of a void pointer is 8 bytes generally but it varies from system to system as if the system is 16-bit, the size of a void pointer is 2 bytes. If the system is 32-bit, the size of a void pointer is 4 bytes. If the system is 64-bit, the size of a void pointer is 8 bytes.

Q17. What is the far pointer in c?

In C, a far pointer is typically 32 bit that can access memory as well as the information which is outside the current segment. To use this pointer, one must allocate their sector register to store data address in the segment, and also another sector register must be stored within the most recent sector.

Q18. What are binary trees?

Binary trees are the trees whose elements have at most 2 children. It is either empty or consists of a node called the root together with two binary trees called the left subtree and the right subtree. The nodes of a binary tree can be numbered in a natural way, level by level, left to right. It allows fast search, inserts, deletes on a sorted data. It also allows finding the closest item.

Q19. What is auto keyword in C?

C programming language has an auto keyword that describes a storage class of local variables inclusive of limited or local lifetime taken from the declaration of its edge to the enclosing scope's (function or block ); as program flow leaves that scope, the variable’s detail discontinue to exist.

An auto keyword indicates that the variable’s kind that in actuality stated will be undoubtedly subtracted against its initializer. For functions, if the return type of them is auto, then such will be assessed through return type language at runtime.

Q20. What is l-value and r-value?

In C, l-value is also known as the locator value that represents an object that occupies some identifiable location in memory. These are the expression which can be placed on the left-hand side of the assignment operator. Whereas r-values are defined by exclusion which means rvalue is an expression that does not represent an object occupying some identifiable location in memory.

Q21. What is a segmentation fault?

In C, a Segmentation fault is a specific kind of error caused by accessing memory that does not belong to you. It is a common condition that causes programs to crash and is caused by a program trying to read or write an illegal memory location.

Q22. What is the output of below code in C: y = 4 || -1 && 0?

The output of below code in C: y = 4 || -1 && 0 is "1".

Q23. What is a scope resolution operator in C ?

The scope resolution operator can be represented as ( :: ). It is used to get hidden names due to variable scopes so that you can still use them. It is also used to define a function outside the class and used to access the static variables of the class.

Q24. What is the use of extern in C?

The keyword "extern" is utilized to enhance the clarity of variable or function. The functions are by default discernible all through the program. There is no obligation to define or declare extern functions. It only escalates the redundancy. Variables including extern keywords are not defined but solely declared.

It shows that a variable stated in one C programming file can further be utilized in another C programming file when you are compiling together the two files. Extern keyword being a modifier can be utilized with all types of data such as float, double, int, pointer, structure, function, and array, etc. Extern keyword is the default repository class of entire functions and global variables.

Hence you may utilize an extern when you desire to utilize a variable that indeed is stated in some different module with that you are linking.

Q25. What are Derived data types in C ?

Aggregation of data type that is fundamental in nature is known as derived data. Derived data types include arrays, unions, structures, enumeration, and pointers. The data are defined by the user just like defining a class in a structure or C++. Pointers store the address of the variables in the data. Array stores related type of data. Structure helps to place different types of items into single type groups.

Derived data types are a structure where all the members are in union and share the same location of memory.

Q26. What are bit fields in C ?

In C, a bit field is a data structure used in computer programming and it consists of a number of adjacent computer memory locations which have been allocated to hold a sequence of bits, stored so that any single bit or group of bits within the set can be addressed.

Q27. What is bit masking in C?

Masking is an act of applying a mask to a random value. A bit masking help to identify which bits are necessary and which bits are not. Bit masking is accomplished by applying:

  • To take out a subset of the bits in the value-Bitwise ANDing
  • To put a subset of the bits in the value-Bitwise ORing
  • To pin a subset of the bits in the value-Bitwise XORing

Application of mask to the value means clearing the first 4 bits and keeping the last 4 bits. By using the operators & and >>, high order bits inside a word as a first byte can be defined. In other words, bit masking means changing or keeping or removing a preferred information part.

Which is better?

C C++
C was designed by Dennis Ritchie between 1969 and 1973 at AT&T Bell Labs. C++ was designed by Bjarne Stroustrup in 1979.
C follows the procedural style programming. It supports both procedural and object-oriented, therefore it is known as multi-paradigm language.
C does not support object-oriented programming; therefore, it doesn’t support polymorphism, encapsulation, and inheritance features. Being an object-oriented programming language C++ supports data abstraction, polymorphism, encapsulation, and inheritance features.
Data is less secured in C. While in C++, you can use modifiers to make the data unreachable for outside users.
C, being procedural programming, it is a function-driven language. While, C++, being object-oriented programming, it is an object driven language.
Exception handling is not directly supported in C. It has to perform using other functions. C++ supports exception handling. Use Try and Catch blocks to correct hard errors.

Advantages of C:

  • Building Block: The programming language C is the most proficient language, the programs written in the C language act as a building block for other programming languages. Also, the essential principles of C language are used in other languages. Many programming languages such as Python, Java, C++, etc. Are designed on the base of C.+
  • Structured Language: The C language is a procedural-oriented language which means complex problems are divided into structures or blocks. It consists of functions modules or blocks that completes a program. This structure helps to debug and test the program easily. Along with that, C language also supports built-in functions written in the C library to develop the program.
  • Portable Language: Being a very flexible language, it never creates a problem to run on any machines. That is, it is machine independent language and the C program can run on any machine with few changes or even no changes.
  • Use of Algorithms and Data Structures: The implementation of data structures and algorithms make the computation fast and easy. With data structures, you can create your own user-defined data types to solve a specific problem. And, Algorithms let to solve your program in less complexity and run time. Moreover, C language can be used in complex problems and operations like in MATLAB.
  • Middle-Level Language: C language id middle level language that means it favors low-level programming as well as high-level Programming. For low-level programming, it supports the use of kernels and drivers, and for high-level programming, it supports system software applications.
  • Easy to learn: C language is a very efficient language as it has many data types and operators to perform all kind of operations. Therefore, a beginner can easily learn it and use it in his/her project very easily. The syntax is similar to the English language which is easy to remember and use. Thus, C language is used as a basis to learn other complex languages.
  • System Programming: C programming language is designed for a system-based approach. This means, programming is done for system hardware specifications and that let us know how high-level language interacts with the machine.

Disadvantages of C:

  • OOPs concept: C is a robust language but it doesn't support concepts of OOPs such as inheritance, polymorphism, encapsulation, data hiding, and abstraction. It just supports a procedural programming approach means every algorithm is a set of function calls.
  • Run type and strict type checking: since, C language does error checking mostly at compile time, so the errors are not detected after each line. The compiler doesn't allow run time checking, means all errors after writing the whole programs that create difficulty in large programs. Along with this, there is no strict type checking means when parameters are passed, no confirmation is processed
  • Exception Handling not supported: It is obvious that bugs and anomalies occur while compiling the programs. Exception Handling is the feature that allows to catch the errors and take suitable responses. But C doesn’t support this important feature.
  • Namespace concept: A namespace is a structured or chain of commands that allow you to reuse the same names in different contexts. It is supported by C++ but not implemented by C. Thus, in C we can't use the same names in declaring variables.

About Author :

  • Author of Advance C Programming Interview Questions

    Pradeep Kumar

    Pradeep Kumar is proficient python programmer with experience in different technologies like Python Django, Scrapy, Angular JS and others languages. He have also worked on customization of test automation using Katalon Studio based on Groovy Language.

Leave A Comment :

Valid name is required.

Valid name is required.

Valid email id is required.