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LEX Code to remove the comments from any C-Program given at run-time and store into ‘out.c’ file

In this article, we going to learn how to create LEX program to extract comment (single line and multiline) from c program?
Submitted by Ashish Varshney, on March 25, 2018

For achieve to this task we create some rules in rule section in the code.

    Input file:
	    /*this in multiline comment
	    We are going to remove this*/

	    // this is single line comment
	    int main()
	    {
		    Code goes here
	    } 
    Output file:
	    int main()
	    {
		    Code goes here
	    } 

/*Definition Section*/
%{
#include<stdio.h>
%}


/*Rule Section*/

%%
/*Regular expression for single line comment*/
\/\/(.*) {};					
/*Regular expression for multi line comment*/
\/\*(.*\n)*.*\*\/  {};			
%%

/*call the yywrap function*/
int yywrap()
{
return 1;
}



/*Auxiliary function*/
/*Driver function*/

int main()
{
yyin=fopen("input6.c","r");
yyout=fopen("out.c","w");
/*call the yylex function.*/
yylex();
return 0;
}

Input

Output