Lexical analysis for GATE CS

By : Manglika Tripathi

Updated : Feb 28, 2021, 0:37

Lexical analysis is like a gateway where the lexical analyzer accepts the input from the source code, breaks them into tokens, and checks whether they are according to their language's grammatical structure. If any token is found invalid, it displays an error message otherwise passed to the syntax analyzer for further analysis. Going by the Lexical analysis book, you must know the types of tokens and converting source codes into tokens. Lexical analyzers sit between the source code and the syntax analyzer and act as the regulatory gateway.

Lexical analysis GATE questions come in many exams, including CAT, GATE CS, PDU CS, SDE interviews, and more. Lexical analysis online tests also form a part of various state and national level exams.

Important Lexical Analysis Topics for GATE

The lexical analysis is a broad topic and has a considerable syllabus. The major topics for Lexical analysis study material for GATE CS are given below.



Specification of Tokens

The tokens can be of different forms such as alphabets, strings and special symbols.

Longest Match Rule

Among all the tokens available, the lexemes are determined based on the longest match of tokens.


It is the finite set of strings that can be shown by regular expressions.

Tips to Solve Lexical Analysis Questions in GATE Exam

The following are some tips that you can follow while solving lexical analysis questions. Prepare for the topic by solving last year question papers well.

  • Lexical analysis GATE questions and answers PDF are based on reading any given set of codes from the source code. Hence, you should focus on the compiler translation part for lexical analysis topics.
  • Prepare excellent lexical analysis notes for the GATE that contains all the details of the syntactic analysis. Those lexical analysis GATE notes will help you in revisions.
  • Practice on lexical analysis online quiz from online sites. These online tests help you in preparation for the real exam.
  • Be clear with the lexical analysis topics for GATE CS as many repetitive topics such as tokens and their types.

Importance of Lexical analysis in GATE Exam

Here's why lexical analysis is an integral part of the GATE and other competitive exams:

  • It checks whether you can run the lexical analysis between the source code and the syntax analyser. It also checks your grasp on the lexical analysis GATE syllabus.
  • The weightage of this topic is 2% to 5% in the exam.
  • GATE requires you to acquire the basic knowledge of lexical analysis algorithms. It helps the processing of any programming languages through the compilers.
  • These concepts are used in real-life situations as a software engineer solving various compiler processes.

Most Recommended Books for Lexical analysis for GATE

The following are some excellent books of Lexical analysis for computer science that can help you prepare for the Lexical analysis syllabus for GATE.

Book Title


Lexical Analysis: Norms and Exploitations

Patrick Hanks

Concepts of Programming

Robert Sebesta

The Theory of Parsing, Translation and Compiling

Alfred Aho

Why Prepare Lexical Analysis from BYJU'S Exam Prep?

It is an online source of knowledge that covers excellent quality tutorials and questions regarding the topic. You can get all the preparatory materials like lexical analysis quiz, lexical analysis MCQ PDF, lexical analysis MCQ questions, and more from BYJU'S Exam Prep website. These preparatory materials are a valuable source to test your exam preparation levels and boost your main exam performance. To prepare well for the exams, our experienced educators have designed lexical analysis notes for CS and lexical analysis notes for GATE PDF for students that help you in the revision.Any student aiming to score maximum marks in the GATE exam should focus well on this part of the GATE syllabus.


Q. How do you understand by lexical analysis?

Lexical analysis is converting data from the source code into tokens that are either accepted or rejected based on the predetermined algorithm.

Q. What is the importance of lexical analysis?

Lexical analysis is the first step of compiling that acts after the source code has been fed into the compiler. It sends the accepted tokens for further processing in the syntax analyser.

Q.Which other exams, lexical analysis is asked other than GATE?

The lexical analysis is an essential topic and is asked in other exams such as PSU CS, CAT, SDE roles, etc. It helps in the understanding of compilers' work.

Q. How many types of tokens are accepted?

The compiler accepts the alphabet, special symbols and the strings as the tokens.

Q. What is the rule priority in the lexical analysis?

Lexical analysers also follow the rule priority. Any reserved words are given priority, such as keywords over the user input.