Raj Kumar
Computer Science And Engineering

Roles of the Lexical analyzer

System Software and Compiler Design

Explanation

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Lexical analyzer performs below given tasks:
  • Helps to identify token into the symbol table
  • Removes white spaces and comments from the source program
  • Correlates error messages with the source program
  • Helps you to expands the macros if it is found in the source program
  • Read input characters from the source program

Example of Lexical Analysis, Tokens, Non-Tokens
Consider the following code that is fed to Lexical Analyzer

#include <stdio.h>
    int maximum(int x, int y) {
        // This will compare 2 numbers
        if (x > y)
            return x;
        else {
            return y;
        }
    }


Examples of Tokens created

 

LexemeToken
intKeyword
maximumIdentifier
(Operator
intKeyword
xIdentifier
,Operator
intKeyword
YIdentifier
)Operator
{Operator
IfKeyword


 

Examples of Nontokens

TypeExamples
Comment// This will compare 2 numbers
Pre-processor directive#include <stdio.h>
Pre-processor directive#define NUMS 8,9
MacroNUMS
Whitespace/n /b /t



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   Raj Kumar
Computer Science And Engineering

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