C language interview questions | Top 10 questions with answers inside!

C programming language is the pioneer of procedural programming languages. Denis Ritchie created the language primarily to write operating systems. C is ‌one of the most popular programming languages in the industry owing to its machine-independent features, high-level abstraction, and structure. If you are seeking employment opportunities in the IT industry, having knowledge and relevant experience in the C language can be beneficial. In fact, in most cases, knowledge of C is compulsory for high-paying opportunities. Keep reading to learn about the top 10 most popular C language interview questions and answers to help you crack the selection process! 

C, as a language, has a plethora of useful applications in the industry, including writing for both application software and system software. As a result, there will be a test on your C language skills during an interview for a prospective job opportunity. 

Practice with the following C interview questions – 

Define C language.  

This is among the most basic C interview questions that you can expect during the selection process. A simple definition, as elaborated below, can demonstrate your foundation in C. 

Answer – C is a mid-level and procedural programming language. It is also a structured programming language that minimizes misinterpretation and error. 

What is a built-in function in C? 

Answer – C’s built-in functions scanf(), printf(), strcpy, strlwr, strcmp, strlen, and strcat are among the most frequently used. Built-functions, which are also referred to as library functions, are system-provided features that aid developers in carrying out a variety of frequently performed predefined tasks. In C, for instance, we use printf() whenever we need to print output or our program to the terminal.

 

What are the features of the C language? 

This is among the C interview questions that will highlight your awareness of the characteristics of the language and of how they are relevant to the industry. Consider drafting a response as follows – 

Answer – One of the most important features of the C language is that is a mid-level programming language that is portable or ‘machine-independent’. It also has a function-rich library and a dynamic memory management system. 

Why is the C language called a mid-level programming language? 

This is a particular type of C interview question that assesses how firm your technical knowledge of the language is. 

Here is a good example of an answer to this question – 

Answer – The C language has characteristics of both low-level (or assembly-level) and high-level languages. As a result, C is common as a middle-level language. 

What is a ‘dangling pointer variable’ in the C language? 

This is among the C interview questions that test how adept you are at identifying the different aspects of the language just by the mention of their technical terminology. 

Your response can be as follows – 

Answer – A pointer in the C programing language points to the memory location of an existing variable. In case the particular variable is deleted and the pointer is still pointing to the same memory location, the pointer variable is referred to as a ‘dangling pointer variable’. 

What are syntax errors? 

This is another example of C interview questions that help interviewers determine how adept you are at technical terminologies. 

The answer to this question is as follows – 

Answer – The errors or mistakes that occur while creating a program are syntax errors. Incorrect case commands misspelled commands, or data type mismatches are common examples of syntax errors. 

Supporting your answer with an example can be beneficial in such a question. 

What is the use of the printf() function? 

This is among the types of C interview questions that assess your working knowledge of the language. Experience with C can help you answer this question. 

Answer – The printf() function is used to print string values, float, a character, or an integer onto the screen. 

State one key difference between a local variable and a global variable. 

These ‘state the difference’ type C interview questions are a test to determine how expansive your knowledge is and if you can compare two different concepts. 

Answer – A local variable is a variable that is declared inside a block or function. In contrast, a global variable is a variable that is declared outside a block or function. 

What is the use of printf() and scanf() functions? Also explain format specifiers? 

Answer –

• printf() is used to print the output on the display.
• scanf() is used to read formatted data from the keyboard. 

The following are some datatype format specifiers that can be used for both printing and scanning:

• %d: A datatype format specifier that can be used to print and scan an integer value.
• %s: It is a string-printing and string-scanning format specifier for the datatype.
• %c: It is a character value display and scanning datatype format specifier.
• %f: A float value can be displayed and scanned with the help of the datatype format specifier %f.

Can a C program be compiled or executed in the absence of a main()? 

Answer – The program can be compiled in the absence of a main() but cannot be executed. 

Key takeaways 

• The IT industry is once again seeing a surge in employment opportunities post the COVID-19 pandemic. 
• This has resulted in the demand for professionals who have the relevant technical skills needed to cater to the growing requirements of the international market. 
• Therefore, knowledge of the C language is among the most commonly probed concepts in an interview for a technical role. 
• Practicing for your interviews with the above 10 C interview questions can help you put your best foot forward on the final day!

We hope you enjoyed reading this blog. In case of any queries, reach out to us or drop a comment below!

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FAQs 

Q1. Where can I learn the C language? 

Answer – There are several online certification courses and short-term diploma courses available that you can choose from to learn the C language. 

Q2. Is C language experience compulsory? 

Answer – While this depends on the role you are applying for, basic industry experience in the language can come in handy for more promising opportunities. 

Q3. Why is the C language called a portable language? 

Answer – C language is called a portable language because the code written in one machine can be moved to another. This is a very important and powerful feature that suits the demands of the industry and market.