Lexical Analyzer for C++ written in C++.

Table of Contents:

• About this project
• Tokens
• How Lexical Analyzer functions
• How to Run this Project
• Assumptions for Subset of C++
• Sample Source Code
• Screen Shots

About this project:

This project is a lexical analyzer generator written in C++. Lexical Analysis is the first phase of the compiler also known as a scanner. It converts the High level input program into a sequence of Tokens.

Tokens:

A lexical token is a sequence of characters that can be treated as a unit in the grammar of the programming languages.

Example of tokens:

• Type token (id, number, real, . . . )
• Punctuation tokens (IF, void, return, . . . )
• Alphabetic tokens (keywords)

How Lexical Analyzer functions

1. Tokenization i.e. Dividing the program into valid tokens.
2. Remove white space characters.
3. Remove comments.

How to Run this Project:

1. Clone the project using command: git clone https://github.com/Akshit6828/Lexical-Analyzer.git
2. Change directory to Lexical-Analyzer using command: cd Lexical-Analyzer.
3. Make a text file in this folder and write source code in C++. 3.1 Try the source code written written here
4. Open Lex.exe file by double clicking on the file.
5. You'll see all associated tokens from the source code.

Note: This is a Lexical Analyzer for a particular subset of C++ language explained under Assumptions: . It may not be able to parse the all token of C++ language.

ASSUMPTIONS:

While designing the LexicalAnalyzer, I have assumed the following assumptions for my Language:

• Special Symbol: ; { } ( ) , #
• Keyword: int, char, float, bool, cin, cout, main
• Pre-processor Directives: include, define
• Library: iostream, studio, string
• Operators: *, +, >>, <<,>,<
• Numbers/Integers: 0 to 9.
• Identifies/ Variables: All alphabetic strings except the keywords, numbers, Pre-processor directive and library strings.

Sample Source Code:

MySourceCode.txt

#include <iostream>
#define LIMIT 5
using namespace std ;
int main(){
    // this comment is written by akshit mangotra for lexical analyzer to avoid reading the comments
    int A , B ;
    cin >> A >> B;
    cout << A * B ; 
}

Screen Shots:

MySourceCode.txt

Output(Console)

OutputFile.txt