Prepare for a C Programming Interview; Should I be scared?

If you want to become a programmer, then you won’t be asked questions, which people get normally during their interview. Nobody would be asking about your hobbies or where do you see yourself in five years. The interviewers will ask specific, C programming questions, and if you don’t know their answers, then you will face difficulty.

This article will offer you a series of expected C programming questions, and their possible answers. If you are going for an interview, then consider this a quick guide for your assistance.

Name the four storage class specifiers in C programming.

Ans: Auto, register, static and extern.

  • What are the basic data types that are used for classifying C Language?

Ans: The data types that are linked with C are Int, which represents the integer and float, a number which has a fraction part. Double is a basic data type, which represents double-repcision floating-point value, and char is for a single character. As for Void, it is a special purpose data type, which doesn’t have any value.

  • Explain the key feature of the C programming language.

There are five key features of the C programming language. The first is portability, which means that the C language is a platform independent language. The second feature is modularity, where the programmer can break down larger program into small modules, using the language. The third is flexibility, which means that I as a programmer would be able to control the language.

Then comes speed, which refers to the support that C language gives to the system. When it gives support to the system, then it is compelling and can be executed at a high speed, as compared to other programming languages. The last one is extensibility, which is adding new features to the language; here is where the creativity of a programmer is checked.

  • Define scope of the variable and what it means in the context of C programming.

The scope of the variable is a part of the code area, where the variable in a program can be accessed without a second medium. In C programming, the identifiers are statically scoped.

  • Let’s take a tricky question here. If you compile a program in C, what happens?

If you are compiling a program in C, then you will witness a multi-stage process. This process will consist of the source object file, which is compiler. It connects to object file, which then connects to the linker. The linker in this lope is a library file, and it leads to an executable file.

  • Why are header files used in C?

Header files are used in C, because they contain the definition, as well as set of rules for the functions that are used in programs. For example, when you are using the printf and scanf on the program, then you have to include the stdio.h library function. If you don’t include this function, then the compiler will give you an error. This is mainly because both the input mentioned, are stored in the header file, and every header file has predefined functions in it.

  • What are syntax errors?

When you are creating a program, and there are mistakes within that program, those are called syntax errors. Syntax errors are usually misspelled commands, or the wrong number of parameters and case commands. Moreover, if the programmer mismatches the data type, then this could be a syntax error as well.

  • What are reserved words?

Reserved words in C language are those, which can’t be used for anything other than their intended purpose. For example, programmers can’t use void and return int. just anywhere; the programmer has to know their intended use and function.

  • There are 32 keywords used in C programming; explain some of them.

The first keyword is void, and it is a special data type. It means an empty data type and doesn’t hold any value. It is mainly used as a return data type for different functions, and is a representation of that function.

The second keyword is extern, which is used for declaring a variable. When extern is used, then it means that the variable is not within the same block where it is used, but elsewhere. It is a global variable and has a legal value and it can be accessed using a function or a block of the program.

As for typedef, it is used for the creation of a new data type, which is an equal of the existing data type. To declare variable, the new data type can be used.

The static keyword represents a static variables, which can preserve their value even if they are out of scope. These variables are initialized once, and exist, until a program ends. No memory ever gets allocated, because they are not declared again. As for Const keyword, it can be used for declaring those variables, which are initialized once and they don’t change their value, ever.

  1. What do you think Memory Leak in C means?

When a programmer creates a memory and then forgets to delete it, that is when a memory leak occurs. A memory that the programmer forgot to delete, can directly impact the efficiency of a system, and it may not perform well.

  1. What is the difference between static memory allocation and dynamic memory allocation?

Dynamic memory allocations happen at runtime and static memory allocation happens at compile time. Static memory can’t be increased, when a programmer is executing a program, but dynamic memory allocation can be increased. While static is specifically used in arrays, dynamic is used in Linked Lists. Dynamic uses less memory space, as compared to static memory.

  1. What is ++a and how is it different from a++?

While a++ uses postfix increment, ++a uses prefix increment. In prefix increment, the value that is assigned to ‘a’ increases and is then given to the same variable. While in postfix increment, the ‘a’ gets an increment, when a particular line is executed.

  1. State a valid place where you can apply the Break Control Statement?

The Break Control Statement can be used in Switch control statements or a loop.

  1. Why is there a dangling pointer in C programming?

There is a dangling pointer in C programming, because it points to the memory address of a variable. Programmers can delete a variable from a memory allocation, while pointing the pointer to the location of the variable.

  1. What is a prototype function in C programming?

A prototype function sends three types of information to the compiler. The information includes the name of the function, its return type and parameters list. For example, if the screen shows ‘int Sum(int,int), then the name of the function here is Sum, the integer data type is the return type and there are two integer parameters.

  1. What is the main difference between actual parameters and formal parameters?

If parameters come from the main function of a subdivided function, then that is an actual parameter. There are parameters which are declared as subdivided function, and they basically end; they are called formal parameters.

  1. What is the importance of ‘main’ in C programming?

Main is very important in C programming. A program can be compiled by the programmer, but without the main, the program can’t be executed.

  1. How would you define nested structure and C token?

When a data member of one function, is referred by the other, then that is called Nested structure. As for C token, the keywords, special symbols and strings that are used in C programming are called C Tokens. They also include constants, operators, and identifiers.

  1. How would you differentiate between arrays and pointers?

The elements that are of similar data types are known as arrays. Pointer, on the other hand, is a variable which stores the location of another variable. The number of variables that an array can store depends on its size, while the pointer variable has only one variable in it. Programmers can initialize arrays at the definition, but they can’t initialize pointers.

  • How are structure and union different from each other?

A programmer can access every member of a structure, simultaneously. However, a union can only access one member at a time. Even if you alter the value of one member, it won’t affect the others in a structure, but it is the opposite for a union. A union variable doesn’t require much memory, as compared to a structure variable, even if it is of the same time.

  • Is the NULL pointer the same as a dangling pointer?

The NULL pointer is different from a dangling pointer, because it is used for indicating that the pointer is not pointing towards a valid location. If programmers don’t know the value of a pointer, then it is best to initialize it is as NULL.

  • How would you define the concept of commenting out?

In coding, coders block code in comment symbols and then delete them, when they are debugging. This way, they are able to isolate a part of the code, which is the main reason for an error. This commenting out concept saves time, because if a code is not the cause behind an issue, then it can be uncomment.

  • What is a loop statement?

A loop statement allows executing groups of statement in a repeated way. There are four types of loop statement; while loop, for loop, do..while loop and nested loop. In a loop diagram, for example, there will be a code statement; if the condition of the code is true, then that code will be used, but if it is false, then the programmer has to come up with a new code statement. Similarly, such a loop contains a nested loop, which means a loop running, within another loop. The first loop is known as outer loop and the second is the inner loop.

  • Define a sequential access file.

When a programmer is developing a program, he will notice that in general programs, new data is stored and existing data is retrieved from files. When a file is saved in a sequential pattern, then this means that to retrieve data from one file, the programmer has to go through all the files, one by one. This is the only way for the programmer to find out the required information.

  • Why do programmers need C program algorithms?

Before a solution is created, an algorithm for that solution is a must. The algorithm creates a guideline on how a problem can be solved. This algorithm contains steps for consideration, along with required calculations that are carried out within a program.

These questions are going to help you prepare for your C programming interview. Even though you do C programming every day, there are some things that you need to read up, before you go to an interview. This is because, interviewers are mostly going to ask you theoretical questions, and at times, transferring practical information into theory can be difficult.

Reading the answers to these questions, would give you a fair idea about what interviewers expect from an interviewee. When you read the answers, you will be able to answer the interviewer better. You won’t hesitate, or appear to not know anything. These questions will also help you revise on your C programming knowledge.

When you go for an interview, make sure that you are confident when you enter, and while you are speaking. If you have faith that you know C programming-related information, then that faith will show on your face. Knowing definitions of specific terms are important, because at times interviewees don’t expect recruiters to ask basic questions. These basic questions determine whether the foundation of your information is solid or not. If you face problem during a question, and don’t know how to answer it, try giving an example.

You can give examples about how you used a specific term, while you were programming. This way, the interviewer will know that you have used the concept practically, and he would be more impressed by your knowledge.

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