Once your CV impresses the employer and asks you to meet them, what should you do? First, you probably feel nervous knowing that the essential part of landing that coveted job is to ace the interview. And you can ace the discussion only if you are fully prepared.
If you have applied for a Programming job, the recruiter or employer may start with the traditional behavioral questions before asking you the technical ones – the programming interview questions. These technical questions can range from the fundamentals to the more challenging higher levels, depending on the position you have applied for.
In this article, we have put together the Top 50 Programming Interview Questions frequently asked programmers of different experience levels.
Some of the programming or coding interview questions can include the following:
1. What do you understand about computer programming?
Computer programming involves writing a set of instructions for a task that a computer can perform. In addition, it requires designing specific algorithms in programming languages for the instructions to be understood by the machine. Programming is also known as coding and includes coding, updating, maintaining, debugging, designing, writing, etc.
2. Can you explain how computer programming works?
The process of computer programming involves the execution of commands for the computer to perform specific tasks. These commands are written instructions that are designed using specific algorithms in programming languages.
3. Can you classify the programming languages?
This is one of the common programming interview questions for beginners. The programming languages are classified as
- High-Level: The programming languages – C, C++, Java, Python are human-friendly and consist of instructions in basic English.
- Low-Level: The programming languages, Assembly Language and Machine-Level languages contain mostly the machine-understandable language of 0s and 1s.
4. What is meant by debugging?
Debugging is the process by which a program is thoroughly checked for errors or bugs. Once the errors are found in the code or logic by the Debugger software, the programmer can point out the errors and remove them.
5. What are the different types of errors that can occur during the execution of a program?
Another of the common programming interview questions – the three types of errors that can occur during the execution of a program are:
- Syntax error
- Runtime error
- Logical error
6. When does a syntax error occur?
When a program violates one or more of the grammatical rules of the programming language, a syntax error occurs.
7. What makes a runtime error occur?
A runtime error only occurs during the implementation of a program when an illegal operation is asked to be performed by the program. The execution of the program then stops immediately, and a diagnostic message appears.
8. What are some of the common runtime errors?
The common runtime errors are – memory leaks, dividing by zero, referencing missing files, calling invalid functions, out-of-range array index, etc.
9. What makes a logical error occur?
The most difficult of all to find, a logical error occurs when a program implements the wrong logic. It is considered the most difficult error to locate because no error messages are reported by the translator, compiler, or interpreter.
10. What is a flowchart?
A pictorial representation that explains the flow of control and algorithm data in a program is called a flowchart.
11. Explain algorithms.
Algorithms are a finite number of steps that, when followed correctly, allow accomplishing a particular task. Therefore, algorithms must be limited, clear, and compelling. This concept is a staple in programming interview questions.
12. What are variables?
Variables are memory cells used to store the value/input of the program and its computational results when a program is executed. The values may change during the execution of the program.
13. What do you mean by reserved words?
Reserved words are words that have pre-defined meanings. Their uses have been pre-defined and cannot be changed or used for any other purpose within the programming language. Some examples include:
- IF
- ELSE
- THEN
14. Define loops.
Sequences of instructions that keep repeating as long as the conditions (given) are satisfied. For loop, while loop and do-while loop are the three types of loops. The for and while loops are entry-controlled, while the do-while loop is exit-controlled.
15. What is the function of a Compiler?
A Compiler processes statements that have been written in a specific programming language and convert them into ‘code’.
16. What is the purpose of Documentation?
Documentations list the detailed description of the program’s design, algorithm, coding methods, testing, and proper use. It is usually valuable for users who rely on the program daily and for the programmer who may modify and update it.
17. What are constants? What are the types of constants?
A quantity whose value cannot be changed or modified is called a constant. Numeric and String are the two types of constraints.
18. What are Numeric Constants?
Integers, single-precision, and double-precision numbers are Numeric Constants. Integer constants have values that can be counted and do not contain any fractions.
19. What are String Constants?
When a sequence of alphanumeric characters is enclosed within a double quotation, it is called a string. A string constant can have only a maximum length of 255 characters.
20. What are the data types used in coding?
The understanding of this concept is a must to ace all programming interview questions. Every variable that is used in a program is assigned a data type. For example, if the data are numbers, then they would be included in ‘int’ datatype. ‘string’ is used for letters, ‘char’ is used for words, ‘bool’ is used for Boolean true and false, ‘float ‘is used for decimals, etc.
21. What are the functions of operators?
Operators define the function that occurs between variables, two or more, or numbers. They are of many types – mathematical operators, conditional operators, logical operators, relational operators, Boolean operators, etc.
22. Show some of the different types of operators,
The mathematical operators include: +, -, *, etc.
The logical operators include: AND, OR, etc.
The conditional or relational operators are: = =, >, <, >=, <=, etc.
23. List some programming languages.
In a set of programming interview questions, you should expect this question. There are several programming languages. The ten most popular ones are listed below:
- Java
- Python
- C
- Ruby
- JavaScript
- C# (pronounced C sharp)
- PHP
- Objective-C
- SQL
- HTML
24. What is the importance of software testing?
Software Testing is the process by which software is tested under specific conditions to assess its quality. This process is also essential to check whether the software provides the expected user experience, meets customer requirements, and can be suitably implemented. (A must ‘know’ from a programming interview questions checklist)
25. And what is a Beta version?
A Beta version of a software is the next version after the Alpha version and before the version before its final release. The Beta version is changed or modified depending on the feedback from the users.
26. What is a Modeling Language?
An artificial language used to express information, knowledge, and systems in an arrangement defined by reliable rules is a Modeling Language. These rules are also used to interpret the meaning of the components in the language structure.
27. What are some of the modelling languages?
Some of the modelling languages are listed below: (You should expect these types of programming interview questions)
- Behaviour Trees
- Business Process Modeling Nation (BPMN)
- C-K Theory
- DRAKON
- EXPRESS
- Extended Enterprise Modeling Language (EEML)
- Flowchart
- Fundamental Modelling Concepts
- Jackson Structured Programming
- LePUS3
28. What do you understand about Machine code?
Machine code is a language processed directly by a microprocessor and does not require any transformation before its use. Programmers don’t write programs in machine code.
29. Can you explain the Fibonacci search? (A must know from a set of programming interview questions)
A search algorithm that applies to sorted arrays is called a Fibonacci search. To reduce the time to search for the target element, a Fibonacci search uses a divide-and-conquer method.
30. Explain the difference between Actual Parameters and Formal Parameters.
Actual Parameters are those parameters that are sent from the primary function to the sub-divided process. The Formal Parameters are the parameters that are used to define the process..
Some of the core JAVA interview questions can include the following: These are common programming interview questions.
31. What is an array?
A data structure storing multiple elements of a data type is called an array. The data structure is stored in a reserved, sequential manner. The three types of arrays are:
- One Dimensional
- Two Dimensional
- Multi-Dimensional
A conventional array is one-dimensional with only one index. A multi-dimensional array is used when one-dimensional indexing is insufficient and multiple indexing is required.
32. Explain the process of memory allocation of an array?
The process of memory allocation occurs during the runtime of programs. The size of the array is continuously adjusted during the program’s runtime and hence does not have to be specified when the program is being written.
33. Define Object-Oriented Programming
Object-Oriented Programming (OOP) is a software design model that focuses on data and objects rather than function and logic. Programmers manipulate the objects and not the reason. Some OOP programming languages are C++, Java, JavaScript, Ruby, NET, PHP, Scala. (A must ‘know’ from the set of programming interview questions).
34. Define JAVA
JAVA is a platform-independent programming language. The high-level programming language was developed by Sun Microsystems and is a collection of objects. Several applications, websites, and games have been developed using JAVA.
35. Explain the features of JAVA. A must know from the set of programming interview questions.
The features of JAVA include:
- OOP Concepts: Object-oriented, Inheritance, Encapsulation, Abstraction, Polymorphism
- Platform-independent
- High- Performer
- Multi-threaded
36. What are the JAVA IDEs?
Eclipse and NetBeans are the Java IDEs
37. What is meant by Constructor?
Constructor is invoked when a new object is made in a program. It has the same name as the class and is produced by default if the user doesn’t create it. A constructor can be overloaded.
38. What is a Class?
A Class defines all JAVA code and has variables and methods. The state of Class is defined by variable attributes. The place of business logic is called the methods and contain specific statements or instructions to satisfy exact requirements.
39. Define an Object
An object is an instance of a class that has a state and behaviour. Every time the JVM reads the “new()” keyword, it creates a class instance.
40. What do you mean by Method Overriding?
Method Overriding occurs when the subclass method satisfies the following conditions of the superclass method:
- same method name
- same argument
- same return type
Some of the core SQL interview questions from a set of programming interview questions can include the following:
41. What is meant by DBMS?
A Database Management System (DBMS) is a program to control the creation, use, and maintenance of a database. It is often referred to as the File Manager because it manages the data in the database rather than in the file systems. Database is an organized form of data that can be easily accessed, stored, retrieved, updated, and managed.
42. Define SQL? (A must ‘know’ from a set of programming interview questions)
The full form of SQL is Structured Query Language, and it communicates with the Database. SQL is a standard language and is used to retrieve, update, insert, and delete data from the database.
43. Differentiate between tables and fields.
A data set that is organized in Columns and Rows is called a table. Columns are vertical while Rows are horizontal. Every table has a specific number of columns known as fields, and any number of rows is called records.
44. What is the Primary Key?
The combination of fields that uniquely specifies rows are called Primary Keys. It is a unique key with constraint NOT NULL implicitly, which means that Primary Keys’ values can never be NULL. Primary Keys have automatic unique constraints.
45. What is a Unique Key?
The Unique Key constraints identify each record in a database. Columns, a Column set, are provided with their uniqueness by the Unique Key conditions. Unique Keys do not have unique automatic constraints defined in them, unlike the Primary Keys.
46. What is Foreign Key?
Foreign Key can be defined as one table that can be related to the Primary Key of another table based on the relationship that has been created between the two tables using specific references.
47. What are Joins and their types?
A Join is a keyword that is used to query data from tables depending on the relationship between fields of tables. Several types of Joins are used to retrieve data and are listed below: (You could also be asked to explain in detail in any programming interview questions set)
- Inner Join
- Left Join
- Right Join
- Full Join
48. What is meant by Normalization, and what are the different types?
The organization of fields and tables in a database to reduce dependency and redundancy is called Normalization. The purposes of Normalization are to add, delete, modify fields that can be made into a single table. The different Normal forms are listed below: (Include this in while answering this programming interview questions).
- First Normal Form
- Second Normal Form
- Third Normal Form
- Fourth Normal form
49. Define a View?
Virtual tables with data subsets contained within tables are called Views. They take less storage space and can contain combined data of one or more tables based on their relationship.
50. Define an Index? What are the different types?
An Index is a performance-enhancing method to allow faster retrieval of data (records) from tables by creating entries for values. The three types of Indexes are listed below: (You can also be expected to answer in detail about each Indexes in programming interview questions).
- Unique Index
- Clustered Index
- Non-Clustered Index
The above set of questions and answers represent only a small portion of the possible programming interview questions that can be posed to you by the recruiter or the employer. There are loads more that you can research on the internet (search: programming interview questions) depending on your level of experience and the type of job that you have applied for. However, always remember, being prepared for your interview will make you feel more in control, and you will be in a better position to impress your interviewers.
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