Lex Program to remove comments from C program

Lex is a computer program that generates lexical analyzers. Lex reads an input stream specifying the lexical analyzer and outputs source code implementing the lexer in the C programming language.

The commands for executing the lex program are:

lex abc.l (abc is the file name)
cc lex.yy.c -efl
./a.out

Let’s see LEX program to accept string starting with vowel.
Examples:

Input : 
//testing
#include 
int main()
{
 /* multiline comment
    continue....
 */
 return 0;
}

Output :
#include 
int main()
{
 
 return 0;
}

Below is the implementation:

/% Lex Program to remove comments from C program  
   and save it in a file %/ 
/*Definition Section*/ 
%{ 
%}
  
/*Starting character sequence for multiline comment*/ 
start \/\* 
/*Ending character sequence for multiline comment*/ 
end  \*\/ 
  
/*Rule Section*/ 
%% 
  
/*Regular expression for single line comment*/ 
\/\/(.*) ; 
/*Regular expression for multi line comment*/  
{start}.*{end} ; 
  
%% 
  
/*Driver function*/ 
int main(int k,char **argcv) 
{ 
yyin=fopen(argcv[1],"r"); 
yyout=fopen("out.c","w"); 
/*call the yylex function.*/ 
yylex(); 
return 0; 
} 

Output:

My Personal Notes

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Tanmay_Jain

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