Write the following programs with LEX Utility Tool System Programming GTU 2150708

a) Write a LEX program to check whether input symbol is number or character.

Program:-

%{

            #include<stdio.h>

%}

%%

       [a-z] printf("It's a Character...\n");

       [0-9] printf("It's a Number...\n");

%%

int yywrap()

{

            return 1;

}

int main()

{

            yylex();

            return 0;

}

Output:-

[root@SAR117 Desktop]#lex p1.lex

[root@SAR117 Desktop]#gcc lec.yy.c

[root@SAR117 Desktop]#./a.out

d

It's a Character...

6

It's a Number…

b) Write a LEX program to check whether input is multi-digit number or string.

Program:-

%{

            #include<stdio.h>

%}

%%

[a-zA-Z]+ printf("It's  a  Multichar String...");

[0-9]+ printf("It's  a  Multidigit Number...");

%%

int yywrap()

{

            return 1;

}

int main()

{

            yylex();

            return 0;

}

Output:-

[root@SAR117 Desktop]#lex p2.lex

[root@SAR117 Desktop]#gcc lec.yy.c

[root@SAR117 Desktop]#./a.out

hello

It's  a  Multichar String...

226

It's  a  Multidigit Number...

c) Write a LEX program to check whether inputted character is vowel or not.

Program:-

%{

            #include<stdio.h>

%}

%%

[a|A,e|E,i|I,O|o,u|U]+ printf("The Character is a vowel\n");

\n

[^a|A,e|E,i|I,O|o,u|U]+ printf("The Character is not a vowel\n");

%%

int yywrap()

{

return 1;

}

int main()

{

yylex();

return 0;

}

Output:-

[root@SAR117 Desktop]#lex p3.lex

[root@SAR117 Desktop]#gcc lec.yy.c

[root@SAR117 Desktop]#./a.out

A

The Character is a vowel

dd

The Character is not a vowel

d) Write a LEX program to check whether a word starts with vowel or not.

Program:-

%{

            #include<stdio.h>

%}

%%

[aeiouAEIOU][a-zA-Z]+ printf("Start’s  with a  vowel");

[a-zA-Z^aeiouAEIOU]+ printf("Does not start with a vowel");

%%

int yywrap()

{

            return 1;

}

int main()

{

            yylex();

            return 0;

}

Output:-

[root@SAR117 Desktop]#lex p4.lex

[root@SAR117 Desktop]#gcc lec.yy.c

[root@SAR117 Desktop]#./a.out

Hey

Does not start with a vowel

Ink

Start’s  with a  vowel

e) Write a LEX program to count the number of characters, words and lines from a given input file.

Program:-

%{

#include<stdio.h>

int w=0,l=0,c=0;

%}

%%

[a-z]+[ .] {

w++;

c+=yyleng;

}

[\n] l++;

. c++;

%%

int yywrap()

{

return 1;

}

int main()

{

yyin=fopen("inp.txt","r");

yylex();

printf("Characters: %d",c);

printf("Words: %d",w);

printf("Lines: %d",l);

return 0;

}

The File contains:-

Hi

How are you

I am good

Output:-

[root@SAR117 Desktop]#lex p5.lex

[root@SAR117 Desktop]#gcc lec.yy.c

[root@SAR117 Desktop]#./a.out

Characters:22

Words:7

Lines:3

Write a program to implement Lexical Analyzer. System Programming GTU 2150708

Program:-

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#include<ctype.h>

int isKeyword(char buffer[]){

    char keywords[32][10] = {"auto","break","case","char","const","continue","default",

                            "do","double","else","enum","extern","float","for","goto",

                            "if","int","long","register","return","short","signed",

                            "sizeof","static","struct","switch","typedef","union",

                            "unsigned","void","volatile","while"};

    int i, flag = 0;

   

    for(i = 0; i < 32; ++i){

        if(strcmp(keywords[i], buffer) == 0){

            flag = 1;

            break;

        }

    }

   

    return flag;

}

int main(){

    char ch, buffer[15], operators[] = "+-*/%=";

    FILE *fp;

    int i,j=0;

   

    fp = fopen("abc.txt","r");

   

    if(fp == NULL){

        printf("error while opening the file\n");

        exit(0);

    }

   

    while((ch = fgetc(fp)) != EOF){

           for(i = 0; i < 6; ++i){

               if(ch == operators[i])

                   printf("%c is operator\n", ch);

           }

          

           if(isalnum(ch)){

               buffer[j++] = ch;

           }

           else if((ch == ' ' || ch == '\n') && (j != 0)){

                   buffer[j] = '\0';

                   j = 0;

                                     

                   if(isKeyword(buffer) == 1)

                       printf("%s is keyword\n", buffer);

                   else

                       printf("%s is indentifier\n", buffer);

           }

          

    }

   

    fclose(fp);

   

    return 0;

}

Output:-

[root@SAR126 Desktop]# gedit lexicalanay.c

[root@SAR126 Desktop]# gcc lexicalanay.c

[root@SAR126 Desktop]# ./a.out

+ is operator

= is operator

abc is indentifier

[root@SAR117 Desktop]# cat abc.txt

a+b=c

Write a program to study the use of strtok(). System Programming GTU 2150708

Program:-

#include<string.h>

#include<stdio.h>

int main()

{

            char str[80]="A /&string/@of/%$^tokens";

            const char s[12]="/,!@#$%^&* ";

            char *token;

            token =strtok(str, s);

            while(token!=NULL)

            {

                        printf("%s\n",token);

                        token=strtok(NULL, s);

            }

            return 0;

}

Output:-

A

string

of

tokens