Infosys Technical Interview Questions

By | June 26, 2019

Infosys is an Indian multinational company which is well known for its IT department. It could be a dream company for many Indian developers and a very good platform to start your career in the IT department. Here in this article, we have mentioned top tech-related questions that you might face during the interview. This article only covers the tech field questions.

Infosys Technical Interview Questions

Question: Name some High-level programming languages.
Answer: 

  • C++
  • C#
  • Java
  • Python
  • Go
  • Swift
  • PHP
  • JavaScript 

Question:  Sometimes C is considered as low-level programming language why so?
Answer: Though C mainly support the concept of High-level programming language, sometimes it considered as low-level programming language because it allows bit-orientated operation, direct memory access and raw pointers.

Question:  What is a Preprocessor in C?
Answer: The Preprocessor is not a part of the compiler, but a separate step at the time of compilation process.  All those commands we write at the top of the program code that starts with a # symbol is known as Preprocessor in C

Question: Name basic OOP’s concepts
Answer: 

  • Abstraction
  • Encapsulation
  • Inheritance
  • Polymorphism

Question: What are Inheritance and name its types?
Answer: Inheritance is one of the important concepts of OOP’s languages, with inheritance we can inherit the properties of one class into another class, the inheritance concept increases the code reusability of the programming language.

Question: Types of Inheritance:
Answer: 

  • Single Inheritance
  • Multi-Level inheritance
  • Hierarchical Inheritance
  • Multiple Inheritance
  • Hybrid Inheritance
  • Multipath Inheritance.

Question: What are Tokens in C++?
Answer: Tokens are the smallest elements in C++ which make more sense to a compiler. Identifiers, keywords, literals, operators, punctuations and other separators are examples of tokens.

Question: What is the difference between Multi-level and Multiple Inheritance?
Answer: In multi-level inheritance the derived class is derived from another derived class and in the Multiple inheritance single class is derived from multiple base classes.

Question: Give some difference between C++ and Java.
Answer: 

Parameters C++ Java
Platform dependency C++ is platform dependent It is platform independent
Usages It is mainly used for windows software It is used to build applications for different platforms, even web applications
Multiple Inheritance C++ support Multiple Inheritance It does not support in-built multiple inheritance.
Pointer C++ support explicit pointer usages Java does not support explicit pointers

Question: How the Encapsulation and Abstraction are complementary?
Answer: Both encapsulation and abstraction used to serve a similar purpose but in a distinct manner, encapsulation as like its name it is used to wrap the data in a single unit such as class, whereas abstraction deal with the data hiding from the user in the form of class.

Question: What are arrays?
Answer: Answer: An array is the most important data structure and every high-level programming language support this Data Structure. An array is a collection of similar data types which store in a contiguous memory location which make array elements retrieval very efficient and makes it very fast.

Question: What is a pointer in C?
Answer: Pointers in C is a variable that stores the address of another variable and the data type of Pointer variable and another variable should be the same.  Pointers are basically used at the time of dynamic memory allocation.

Question: Give some difference between C and C++ language.
Answer: 

Parameters C++ C
Type C++ is a procedural as well as an Object-Oriented Programming language C is a procedural language
Data security C++ follow the concept of Object-oriented programming language which increases the data security Data is less secure in C
Namespace C++ has the Namespace feature C does not have this feature
Exception handling C++ supports exception handling There is no such feature in

Question: What is a NULL pointer?
Answer: Pointers which points to no Objects, or variables are known as NULL pointers. NULL pointers mostly used to refer to the end point of any data structure such as a list.

Question: Give logic to swap two numbers without using the temporary variable.
Answer: 

{
i = i + j;
j = i – j;
i= i – j;
}

Question: What is a Virtual function?
Answer: Those functions which have a virtual keyword before their name in the base class and redefined in derived class are known as Virtual function. 

Question: What is a pure virtual function?
Answer: A virtual function becomes a pure virtual function if it does not have any definition in the base class and its function declaration is set to 0.

Question: What is the difference between the process memory allocation and deallocation in Java and C++?
Answer: In C++ memory allocation and deallocation is done manually by the developer using the calloc(), malloc(), free() and new functions, while in Java the interpreter takes care of the memory allocation and deallocation of the objects.

Question: What is a heap binary tree?
Answer: A binary heap is a complete binary tree which satisfies the heap ordering property, and it has two types.

  • Min-heap property: In this, each child node has an equal or greater value than parent node and here the root node has the minimum value.
  • Max heap property: Here each child node has a less or equal value to the parent node and here root node has the maximum value.

Question: What is a linked list?
Answer: It is a very famous data structure that often compared with arrays. A linked list is a collection of Homogenous or Heterogeneous data elements which stored at the different memory location.

Question: Give some difference between the linked list and array.
Answer: 

Parameters Linked-list Array
Size type It is dynamic in size Arrays are fixed in size
Data type It can store both homogeneous as well as heterogeneous data types It can only store the same data types.
Speed A linked list is slow as compare to Array Data store at a contagious memory location which makes it faster.
Element Accessibility Random accessibility is not possible in a linked list Random element accessibility is possible in Array with the help of indexing.
Memory efficient Linked-list is more memory efficient data structure. Arrays are not memory efficient data structure.

Question: What do you mean by cross-platform?
Answer: A cross-platform system or software means that product or system can works on different platforms or operating environment these are also known as platform independent systems.

Question: Give some difference between DOS and Windows.
Answer: 

Parameters DOS Windows
Multi-threading DOS is a single tasking OS Windows are designed to perform multiple tasks
User interface DOS uses plain interface basically the console. Windows provide a graphical interface.
Operate It’s very hard to operate DOS you should have knowledge for each command lines It is very easy to operate windows OS because of its graphical interface
Features In DOS we can play games or music Windows provides us features like play games and music
performance DOS is way faster than windows Windows OS speed is very slow.

Question: What is RDBMS?
Answer: RDBMS stands for Relational Database Management System and it is a subset of DBMS. RDBMS is the most efficient amongst DBMS systems because it stores data in the form of rows and columns.

Question: What is the difference between Char and Varchar in DBMS?
Answer: 

Char Varchar
It stores character string with a fixed length It also stores character string with variable length
It has a maximum limit of 255 Characters It has a character limit of 65,535 characters
It is 50% faster than Varchar It is slower than Char
Use static memory allocation technique Use dynamic allocation technique

Question: What is Database Schema?
Answer: A schema of a database is a logical view of a complete database. The database schema represents the data organization and relation in a database, and it used to define the database entity and relations between those entities.

Question: What is DSN?
Answer: Data Source Name (DSN) provides connectivity to a database through an ODBC driver. The DSN contains database name, directory, database driver, UserID, password, and other information. Once you create a DSN for a particular database, you can use the DSN in an application to call information from the database.

Question: What is DNS?
Answer: DNS stands for Domain Name System it is phonebook of the Internet. Domain Name System is used to provides an alphanumeric name to the IP addresses registered on the server.

Question: What is Normalization in DBMS?
Answer: Normalization is a process or technique used on Databases to reduce the data redundancy and increase the dependency of data. It basically used to divide the big table into small tables so the unwanted or repeated data could be removed.

Question: Differentiate between ‘a’ and “a”
Answer: ‘a’ is a character literal and it has a type char with value 97 on most systems.

“a” is a string literal and its type is const char[2] and it refers to an array of size 2.

Conclusion:

In the above article, we have provided top Infosys interviews question that frequently asked in its technical interviews. After reading all questions you will notice that most of the questions are from C and C++ which also includes OOP’s concept with data Structure because these are the basis of each programming language and a developer should have knowledge of basic technical stuff. C and C++ questions also make sense because if you have a degree in Computer science you would have learned these two languages.

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