LEX to count the no of "scanf" and "printf" statement in a c program. Replace them with "writf" and "readf" respectively.

/* declaration section in this sections we will declare the different value and include the header file which we are using in this program to run this program */

%{
#include<stdio.h>
int sf=0,pf=0;
%}

/* defined section */

%%
"scanf" { sf++; fprintf(yyout,"readf");}           // replace scanf  with readf
"printf" { pf++; fprintf(yyout,"writef");}            // replace printf  with writef


%%

int main()
{
yyin=fopen("open.c","r");                            // input file open.c
yyout=fopen("new.c","w");                           // output file new.c with replace 
yylex();

     //no of printf and scanf in the file
printf("Number of scanfs=%d\nNumber of Printf's=%d\n",sf,pf);

return 0;

}

download the file 

  How to run this program 

          save the file as "ass1.6.l" 

          open terminal and run    " flex  ass1.6.l "

          it generates c file run      " cc lex.yy.c -o ass1.6 -ll  "  asoutputt  in file count

          now run   for output       " ./ass1.6"

"open.txt"

#include<stdio.h>

main()

{

int a;

printf("enter the number for sum\n")

scanf("%d",&a);

}

new.txt

#include<stdio.h>

main()

{

int a;

writef("enter the number for sum\n")

readf("%d",&a);

}