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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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