Lex Programs

Program to count
a.  Number of vowels and consonants in a given string.
b.  Numbers of comment lines in a given C program.
c.  Number of
     i. Positive and negative integers
     ii.  Positive and negative fractions
d. Number of characters, words, spaces and lines in a given input file. Also eliminate them and copy that program into separate file.

a)
%{
int v=0;
int c=0;
%}

%%
[aeiouAEIOU] {v++;}
[a-zA-Z] {c++;}
%%

void main()
{
printf("Enter string :\n");
yylex();
printf("vowels :%d\n",v);
printf("consonants :%d\n :",c);
}


b)

%{

#include<stdio.h>

int s=0;

int line_num = 0;

%}

%x comment

%%

"/*"         BEGIN(comment);++line_num;

<comment>[^*\n]*        /* eat anything that's not a '*' */

<comment>"*"+[^*/\n]*   /* eat up '*'s not followed by '/'s */

<comment>\n             ++line_num;

<comment>"*"+"/"        BEGIN(INITIAL);

"//".* ++line_num;

%%

main()

{

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

yyout=fopen("in2.c","w");

yylex();

printf("No. of line=%d\n",line_num);

}

in.c

#include<stdio.h>

int main()//main file

/******

****fdg*/

//

{

int d,e;

printf("printf("b");");

scanf("enter %d",&d,e);

}

in2.c

#include<stdio.h>

int main()

{

int d,e;

printf("printf("b");");

scanf("enter %d",&d,e);

}

c)

Pnif.l

%{

#include<stdio.h>

int p_i=0;

int n_i=0;

int p_f=0;

int n_f=0;

%}

%%

\+?[0-9]+([eE]"+"?[0-9]+)? {p_i++;}

\+?[0-9]+([eE]"-"[0-9]+)? {p_f++;}

-[0-9]+([eE]"+"?[0-9]+)? {n_i++;}

-[0-9]+([eE]"-"[0-9]+)? {n_f++;}

\+?[0-9]+"."[0-9]+([eE]("+"|"-")?[0-9]+)? {p_f++;}

-[0-9]+"."[0-9]+([eE]("+"|"-")?[0-9]+)? {n_f++;}

%%

yywrap()

{

return 1;

}

void main()

{

printf("Enter the numbers \n ");

yylex();

printf("\n no of +ve integers are %d \n",p_i);

printf("\n no of -ve integers are %d \n",n_i);

printf("\n no of +ve Fractions are %d \n",p_f);

printf("\n no of -ve Fractions are %d \n",n_f);

}

 

d)

Count2.l

%{

int lineCount, wordCount, charCount,space;

%}

LETTER [a-zA-Z0-9]

%%

\n     lineCount++;

{LETTER}+    { wordCount++; charCount+=yyleng; }

" " charCount++;space++;

.      charCount++;

%%

int main () {

       yyin=fopen("a.txt","r");

       yyout=fopen("b.txt","w");

       yylex();

       printf ("Input contains \n");

       printf ("%d spaces\n%d lines\n%d words\n%d chars\n",space, lineCount, wordCount, charCount);

       return 0;

}

a.txt

hello how ARE

haha fight

2. Program to count the number of ‘scanf’ and ‘printf’ statements in a C program. Replace them with ‘readf’ and ‘writf’ statements respectively.

prinfscanf.l

%{

#include<stdio.h>

int p=0,s=0;

%}

%x print scan

%%

"printf" BEGIN(print);fprintf(yyout,"%s","writef");

<print>[(]["] fprintf(yyout,"%s",yytext);

<print>[^)] fprintf(yyout,"%s",yytext);

<print>[)] BEGIN(INITIAL); p++; fprintf(yyout,"%s",yytext);

"scanf" BEGIN(scan);fprintf(yyout,"%s","readf");

<scan>[(]["] fprintf(yyout,"%s",yytext);

<scan>[^)] fprintf(yyout,"%s",yytext);

<scan>[)] BEGIN(INITIAL); s++; fprintf(yyout,"%s",yytext);

%%

main()

{

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

yyout=fopen("in2.c","w");

yylex();

printf("No. of scanf=%d\n",s);

printf("No. of printf=%d\n",p);

}

in.c

#include<stdio.h>

int main()

{

int d,e;

printf("printf("b");");

d=e;

scanf("enter %d",&d,e);

}

 in2.c

#include<stdio.h>

int main()

{

int d,e;

writef("printf("b");");

d=e;

readf("enter %d",&d,e);

}

 

 

 Thank You For Reading.

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Also programs you require.