Lab #1 Solution

Lab Objectives

    • To understand the developmental aspects of compiler.

    • To learn the tools, namely Lex and Yacc used in the development of compilers.

Lab Outcomes

    • Ability to write regular expressions for different language constructs.

    • Ability to develop simple tools for scanning and parsing.

    • Ability to develop a miniature compiler.

Exercises

Objective: Learning Lex through simple tasks.

    1. Write a lex program to read a string of digits of arbitrary length from a file and verify whether the given string of digits is a binary, octal, decimal, hexa decimal number or not a valid number.

Test cases:


input    output


01000001    binary

010901    decimal

90878    hexa

010007    octal

010909    decimal

acbd    hexa

0109    decimal

klfw    invalid

abcd    hexa


    2. Write a lex program to read a string of digits of arbitrary length from a file and verify whether given string is Positive/Negative, Integer, Integer with Exponent form, Real, Real with Exponent form. Example: 23, 23, +23, 12e3, 12e3, 12e+3, 12e23, 2.3, 2.3, 3.14E2, 3.12e+2, 3.12e14, 3.13E23.

Test cases:









1
input    output


    12 positive integer

0.10positive real

10.01    positive real

stp
neither integer nor real
0.2.3
neither integer nor real
2..3
neither integer nor real
.23
real
12e3
positive integer in exponential form

12.2e-3    positive real in negative exponential form


    3. Write a lex program to read a string of digits of arbitrary length from a file and verify whether given string is a valid IPv4 address or not

Test cases:
inputoutput

123.234.43.2valid

123.234.43.2.4.3  invalid

257.890.123.978
invalid
0.0.0.0
valid



    4. Write a lex program to check whether given String is valid Email id or not. Specifications: Email id has username and domainname. Domainname may contain subdomains and can have a depth of any number of levels. Username and domainname may contain digits, alphabets and special characters, underscore ( ) and/or dot (.). However username or domainname should not start with underscore and the special characters should not appear consecutively either in domainname or in username. Leading dot and trailing dot in username/domainname is not allowed.

Sample Structure: username@domainname Test cases:
inputoutput


kishan@gmail.com
valid email
kanduru@iittp.ac.in
valid email
kishan123

23@yahoo.co.in
valid email
kishan.gmail.com
invalid email
kishan.@gmail.com
invalid email
.kishan@yahoo.com
invalid email















@gmail.com
invalid email
@%@&*(@gmail.com
invalid email
kishan..kanaut@yahoo.com
invalid email
kishan.kandukuru@yahoo..co..in
invalid email
kishan@abc.gov
valid email
kishan@xyz.abc.gov
valid email
kishan@pqr.xyz.abc.gov
valid email
kishan@x.pqr.xyz.abc.com
valid email
@gmail.com
invalid email
kishan@
invalid email
123890@gmail.com
valid email






















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Submission guidelines

All Exercises should be submitted in the following format.

    • All files and folders should be lowercase letters

    • Create a folder with name yourrollnumber week 1 (say cs17b001 week 1) and create subfolders, namely 1, 2,.., n for each problem given for the first lab, in this single folder

    • Prepare a separate lex and make files for each of the exercise problems

    • Makefile should generate final executable file named scanner

    • The input must be given through a file and the file name should be taken through command line arguments

    • Copy the lex and make files into their respective sub folders

    • Create a Readme file in the main folder

    • Dont keep any unrealed or executable files

    • Finally tar and compress the yourrollnumber week 1 directory as yourrollnumber week 1.tar.gz and upload the same to the course page at Moodle before the due date.


Any kind of copying, sharing code with others, and Malpractices attract high penalties to the extent of referring to the Institute Level Disciplinary committee.

Evaluation is done based on

    • Output

    • Logic (wherever applicable)

    • Naming convention, code readability, comments etc.,

    • Adherence to the instructions



























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