Lex program to add line numbers to a given file and create a new file

Lex program to add line numbers to a given file and create a new file

**************************************************

%{

int line_number = 1;

%}

%option noyywrap

line .*\n

%%

{line} { printf("%10d %s", line_number, yytext); fprintf(yyout,"%10d %s",line_number,yytext);line_number++; }

%%

int main()

{

yyin = fopen("test.c","r");

yyout=fopen("testnew.c","w");

yylex();

return 0;

}

Execution

$cat test.c # input file

#include <stdio.h>

void main()

{

 int a=2,b=4;

 printf("%d",a+b);

}

$flex lnumber.lex

$ gcc lex.yy.c

$ ./a.out

         1 #include <stdio.h>

         2 void main()

         3 {

         4  int a=2,b=4;

         5  printf("%d",a+b);

         6 }

$cat testnew.c # new file created

         1 #include <stdio.h>

         2 void main()

         3 {

         4  int a=2,b=4;

         5  printf("%d",a+b);

         6 }