This document contains the coding for 9 practical assignments related to compiler design. It includes programs to implement a lexical analyzer, parser using lex and yacc tools, symbol table, predictive parsing, bottom-up parsing, computation of First and Follow sets, and checking if a string is a keyword or identifier. It also contains programs for data flow and control flow analysis. The coding shows the implementation of these compiler design concepts in C language.

1. 1 | P a g e

2. 2 | P a g e
PRACTICAL -1
AIM:-To Write a C program to develop a lexical analyzer to recognize a
few patterns in C.
OUTPUT:-

3. 3 | P a g e
PRACTICAL -1
AIM:-To Write a C program to develop a lexical analyzer to recognize a
few patterns in C.
CODING:-
#include <stdio.h>
#include <conio.h>
#include <string.h>
char symTable[5][7] = { "int", "void", "float", "char", "string" };
void main() {
int i, j, k = 0;
char string[7];
char str[] = "int main(){printf("Hello");return 0;}";
char *ptr;
clrscr();
printf("Splitting string "%s" into tokens:n", str);
ptr = strtok(str, " (){};""");
printf("nn");
while (ptr != NULL) {
printf ("%sn", ptr);
for (i = k; i< 5; i++) {
memset(&string[0], 0, sizeof(string));
for (j = 0; j < 7; j++) {
string[j] = symTable[i][j];
}
if (strcmp(ptr, string) == 0) {
printf("Keywordnn");
break;
} else
if (string[j] == 0 || string[j] == 1 || string[j] == 2 ||
string[j] == 3 || string[j] == 4 || string[j] == 5 ||
string[j] == 6 || string[j] == 7 || string[j] == 8 ||
string[j] == 9) {
printf("Constantnn");
break;
} else {
printf("Identifiernn");
break;
}
}
ptr = strtok(NULL, " (){};""");
k++;

4. 4 | P a g e
}
getch();
}

5. 5 | P a g e

6. 6 | P a g e
PRACTICAL -2
AIM:-To write a program to implement the Lexical Analyzer using lex tool.
OUTPUT:-

7. 7 | P a g e
PRACTICAL -2
AIM:-To write a program to implement the Lexical Analyzer using lex tool.
CODING:-
#include<stdio.h>
#include<ctype.h>
#include<conio.h>
#include<string.h>
char vars[100][100];
int vcnt;
char input[1000],c;
char token[50],tlen;
int state=0,pos=0,i=0,id;
char *getAddress(char str[])
{
for(i=0;i<vcnt;i++)
if(strcmp(str,vars[i])==0)
return vars[i];
strcpy(vars[vcnt],str);
return vars[vcnt++];
}
int isrelop(char c)
{
if(c=='+'||c=='-'||c=='*'||c=='/'||c=='%'||c=='^')
return 1;
else
return 0;
}
int main(void)
{
clrscr();
printf("Enter the Input String:");
gets(input);
do
{
c=input[pos];
putchar(c);
switch(state)
{
case 0:
if(isspace(c))
printf("b");
if(isalpha(c))
{
token[0]=c;
tlen=1;
state=1;
}

8. 8 | P a g e
if(isdigit(c))
state=2;
if(isrelop(c))
state=3;
if(c==';')
printf("t<3,3>n");
if(c=='=')
printf("t<4,4>n");
break;
case 1:
if(!isalnum(c))
{
token[tlen]='o';
printf("bt<1,%p>n",getAddress(token));
state=0;
pos--;
}
else
token[tlen++]=c;
break;
case 2:
if(!isdigit(c))
{
printf("bt<2,%p>n",&input[pos]);
state=0;
pos--;
}
break;
case 3:
id=input[pos-1];
if(c=='=')
printf("t<%d,%d>n",id*10,id*10);
else{
printf("bt<%d,%d>n",id,id);
pos--;
}state=0;
break;
}
pos++;
}
while(c!=0);
getch();
return 0;
}

9. 9 | P a g e

10. 10 | P a g e
PRACTICAL -3
AIM:-Design Predictive Parserof the RECURSIVE DESCENTPARSER
OUTPUT:-

11. 11 | P a g e
PRACTICAL -3
AIM:-Design Predictive Parserof the RECURSIVE DESCENTPARSER
LANGUAGE:- E-> TE’
E’-> +TE’ | -TE’ | null
T-> FT’
T’-> *FT’| /FT’ | null
F-> id/ (E)/ num
CODING:-
#include "stdio.h"
#include "conio.h"
char input[100];
char prod[100][100];
int pos=-1,l,st=-1;
char id,num;
void E();
void T();
void F();
void advance();
void Td();
void Ed();
void advance()
{
pos++;
if(pos<l)
{
if(input[pos]>='0'&& input[pos]<='9')
{
num=input[pos];
id='0';
}
if((input[pos]>='a' || input[pos]>='A')&&(input[pos]<='z' || input[pos]<='Z'))
{id=input[pos];
num='0';
}
}
}
void E()
{
strcpy(prod[++st],"E->TE'");
T();
Ed();
}
void Ed()
{
int p=1;

12. 12 | P a g e
if(input[pos]=='+')
{
p=0;
strcpy(prod[++st],"E'->+TE'");
advance();
T();
Ed();
}
if(input[pos]=='-')
{ p=0;
strcpy(prod[++st],"E'->-TE'");
advance();
T();
Ed();
}
// Recursive Descent Parser
if(p==1)
{
strcpy(prod[++st],"E'->null");
}
}
void T()
{
strcpy(prod[++st],"T->FT'");
F();
Td();
}
void Td()
{
int p=1;
if(input[pos]=='*')
{
p=0;
strcpy(prod[++st],"T'->*FT'");
advance();
F();
Td();
}
if(input[pos]=='/')
{ p=0;
strcpy(prod[++st],"T'->/FT'");
advance();
F();
Td();
}
if(p==1)
strcpy(prod[++st],"T'->null");
}

13. 13 | P a g e
void F()
{
if(input[pos]==id) {
strcpy(prod[++st],"F->id");
advance(); }
if(input[pos]=='(')
{
strcpy(prod[++st],"F->(E)");
advance();
E();
if(input[pos]==')') {
//strcpy(prod[++st],"F->(E)");
advance(); }
}
if(input[pos]==num)
{
strcpy(prod[++st],"F->num");
advance();
}
}
int main()
{
int i;
printf("Enter Input String ");
scanf("%s",input);
l=strlen(input);
input[l]='$';
advance();
E();
if(pos==l)
{
printf("String Acceptedn");
for(i=0;i<=st;i++)
{
printf("%sn",prod[i]);
}
}
else
{
printf("String rejectedn");
}
getch();
return 0;
}

14. 14 | P a g e
PRACTICAL -4
AIM:-To write a C program to implement a symbol table.
OUTPUT:-

15. 15 | P a g e
PRACTICAL -4
AIM:-To write a C program to implement a symbol table.
CODING:-
#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
void main()
{
int i=0,j=0,x=0,n;
void *p,*add[5];
char ch,srch,b[15],d[15],c;
printf("Expression terminated by $:");
while((c=getchar())!='$')
{
b[i]=c;
i++;
}
n=i-1;
printf("Given Expression:");
i=0;
while(i<=n)
{
printf("%c",b[i]);
i++;
}
printf("n Symbol Tablen");
printf("Symbol t addr t type");
while(j<=n)
{
c=b[j];
if(isalpha(toascii(c)))
{
p=malloc(c);
add[x]=p;
d[x]=c;
printf("n%c t %d t identifiern",c,p);
x++;
j++;
}
else
{
ch=c;
if(ch=='+'||ch=='-'||ch=='*'||ch=='=')

16. 16 | P a g e
{
p=malloc(ch);
add[x]=p;
d[x]=ch;
printf("n %c t %d t operatorn",ch,p);
x++;
j++;
}}}}

17. 17 | P a g e

18. 18 | P a g e
PRACTICAL -5
AIM:-To design LALR bottom up parserfor the given language.
OUTPUT:-

19. 19 | P a g e
PRACTICAL -5
AIM:-To design LALR bottom up parserfor the given language.
CODING:-
<parser.l>
%{
#include<stdio.h>
#include "y.tab.h"
%}
%%
[0-9]+ {yylval.dval=atof(yytext);
return DIGIT;
}
n|. return yytext[0];
%%
<parser.y>
%{
/*This YACC specification file generates the LALR parser for the program
considered in experiment 4.*/
#include<stdio.h>
%}
%union
{
double dval;
}
%token <dval> DIGIT
%type <dval> expr
%type <dval> term
%type <dval> factor
%%
line: expr 'n' {
printf("%gn",$1);
}
;
expr: expr '+' term {$$=$1 + $3 ;}
| term
;
term: term '*' factor {$$=$1 * $3 ;}
| factor
;
factor: '(' expr ')' {$$=$2 ;}
| DIGIT
;
%%
int main()
{

20. 20 | P a g e
yyparse();
}
yyerror(char *s)
{
printf("%s",s);
}

21. 21 | P a g e

22. 22 | P a g e
PRACTICAL -6
AIM:-To write a C program to find computation of First.
OUTPUT:-

23. 23 | P a g e
PRACTICAL -6
AIM:-To write a C program to find computation of First.
CODING:-
#include<stdio.h>
#include<math.h>
#include<string.h>
#include<ctype.h>
#include<stdlib.h>
int n,m=0,p,i=0,j=0;
char a[10][10],f[10];
void follow(char c);
void first(char c);
int main(){
int i,z;
char c,ch;
//clrscr();
printf("Enter the no of prooductions:n");
scanf("%d",&n);
printf("Enter the productions:n");
for(i=0;i<n;i++)
scanf("%s%c",a[i],&ch);
do{
m=0;
printf("Enter the elemets whose fisrt& follow is to be found:");
scanf("%c",&c);
first(c);
printf("First(%c)={",c);
for(i=0;i<m;i++)
printf("%c",f[i]);
printf("}n");
strcpy(f," ");
//flushall();
m=0;
follow(c);
printf("Follow(%c)={",c);
for(i=0;i<m;i++)
printf("%c",f[i]);
printf("}n");
printf("Continue(0/1)?");
scanf("%d%c",&z,&ch);
}while(z==1);
return(0);
}

24. 24 | P a g e
void first(char c)
{
int k;
if(!isupper(c))
f[m++]=c;
for(k=0;k<n;k++)
{
if(a[k][0]==c)
{
if(a[k][2]=='$')
follow(a[k][0]);
else if(islower(a[k][2]))
f[m++]=a[k][2];
else first(a[k][2]);
}
}
}
void follow(char c)
{
if(a[0][0]==c)
f[m++]='$';
for(i=0;i<n;i++)
{
for(j=2;j<strlen(a[i]);j++)
{
if(a[i][j]==c)
{
if(a[i][j+1]!='0')
first(a[i][j+1]);
if(a[i][j+1]=='0' && c!=a[i][0])
follow(a[i][0]);
}
}
}

25. 25 | P a g e

26. 26 | P a g e
PRACTICAL -7
AIM:-To find whether a given string is Keyword or not.
OUTPUT:-

27. 27 | P a g e
PRACTICAL -7
AIM:-To find whether a given string is Keyword or not.
CODING:-
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char keyword[32][10]={"auto","double","int","struct","break","else","long",
"switch","case","enum","register","typedef","char",
"extern","return","union","const","float","short",
"unsigned","continue","for","signed","void","default",
"goto","sizeof","voltile","do","if","static","while"} ;
char string[10];
int flag=0,i;
printf("ENTER ANY STRING:");
gets(string);
for(i=0;i<32;i++)
{
if(strcmp(string,keyword[i])==0)
{
flag=1;
}
}
if(flag==1)
printf("%s is a Keywordn",string);
else
printf("%s is not a Keywordn",string);
getch();
}

28. 28 | P a g e
PRACTICAL -8
AIM:-To find whether a given string is Identifier or not.
OUTPUT:-

29. 29 | P a g e
PRACTICAL -8
AIM:-To find whether a given string is Identifier or not.
CODING:-
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[100],str[20],str1[10]={"printf"};
int i,l,flag=0,s;
clrscr();
printf("nenter the string:");
gets(a);
if(strcmp(a,str1)==0)
{
printf("nnot allow");
}
else
{
l=strlen(a);
if(a[0]==' '||a[0]=='@')
{
printf("ninvalid identifier");
goto p;
}
else
{
s=0;
while(s!=l)
{
if(a[s]==' '||a[s]=='1'||a[s]=='2'||a[s]=='3'|| a[s]=='4'||a[s]=='5' ||a[s]=='6'
||a[s]=='7' ||a[s]=='8'||a[s]=='9'||a[s]=='0')
{
printf("ninvalid identifier");
goto p;
}
else
{
flag=0;
}
s++;

30. 30 | P a g e
}
if(flag==1)
{
printf("ninvalid identifier");
}
if(flag==0)
{
printf("nvalid identifier");
}
}
}
p:
getch();
}

31. 31 | P a g e

32. 32 | P a g e
PRACTICAL -9
AIM:-To write a C program to implement data flow & control flow
analysis
OUTPUT:-

33. 33 | P a g e
PRACTICAL -9
AIM:-To write a C program to implement data flow & control flow
analysis
CODING:-
#include<stdio.h>
#include<string.h>
#include<ctype.h>
void input();
void output();
void change(int p,intq,char *res);
void constant();
void expression();
struct expr
{
char op[2],op1[5],op2[5],res[5];
int flag;
}arr[10];
int n;
int main()
{
int ch=0;
input();
constant();
expression();

34. 34 | P a g e
output();
}
void input()
{
int i;
printf("nnEnter the maximum number of expressions:");
scanf("%d",&n);
printf("nEnter the input : n");
for(i=0;i<n;i++)
{
scanf("%s",arr[i].op);
scanf("%s",arr[i].op1);
scanf("%s",arr[i].op2);
scanf("%s",arr[i].res);
arr[i].flag=0;
}
}
void constant()
{
int i;
int op1,op2,res;
char op,res1[5];
for(i=0;i<n;i++)
{
if(isdigit(arr[i].op1[0]) &&isdigit(arr[i].op2[0]))

35. 35 | P a g e
{
op1=atoi(arr[i].op1);
op2=atoi(arr[i].op2);
op=arr[i].op[0];
switch(op)
{
case '+':
res=op1+op2;
break;
case '-':
res=op1-op2;
break;
case '*':
res=op1*op2;
break;
case '/':
res=op1/op2;
break;
}
sprintf(res1,"%d",res);
arr[i].flag=1;
change(i,i,res1);
}
}
}

36. 36 | P a g e
void expression()
{
int i,j;
for(i=0;i<n;i++)
{
for(j=i+1;j<n;j++)
{
if(strcmp(arr[i].op,arr[j].op)==0)
{
if(strcmp(arr[i].op,"+")==0||strcmp(arr[i].op,"*")==0)
{
if(strcmp(arr[i].op1,arr[j].op1)==0&&strcmp(arr[i].op2,arr[j].op2)==0 ||
strcmp(arr[i].op1,arr[j].op2)==0&&strcmp(arr[i].op2,arr[j].op1)==0)
{
arr[j].flag=1;
change(i,j,NULL);
}
}
else
{
if(strcmp(arr[i].op1,arr[j].op1)==0&&strcmp(arr[i].op2,arr[j].op2)==0)
{
arr[j].flag=1;
change(i,j,NULL);
} }
} }

37. 37 | P a g e
} }
void output()
{
int i=0;
printf("nOptimized code is : ");
for(i=0;i<n;i++)
{
if(!arr[i].flag)
{
printf("n%s %s %s %sn",arr[i].op,arr[i].op1,arr[i].op2,arr[i].res);
}
}
}
void change(int p,intq,char *res)
{
int i;
for(i=q+1;i<n;i++)
{
if(strcmp(arr[q].res,arr[i].op1)==0)
if(res == NULL)
strcpy(arr[i].op1,arr[p].res);
else
strcpy(arr[i].op1,res);
else if(strcmp(arr[q].res,arr[i].op2)==0)
if(res == NULL)

38. 38 | P a g e
strcpy(arr[i].op2,arr[p].res);
else
strcpy(arr[i].op2,res);
}
}

39. 39 | P a g e

40. 40 | P a g e
PRACTICAL -10
AIM:-To write a C program for Stack to use dynamic storage allocation.
OUTPUT:-

41. 41 | P a g e
PRACTICAL -10
AIM:-To write a C program for Stack to use dynamic storage allocation.
CODING:-
#include<stdio.h>
#include<stdlib.h>
#define TRUE 1
#define FALSE 0
typedef struct Heap
{
int data;
struct Heap *next;
}
node;
node *create();
void main()
{
int choice,val;
char ans;
node *head;
void display(node *);
node *search(node *,int);
node *insert(node *);
void dele(node **);
head=NULL;
do
{
printf("nProgram to perform various operations on Stack using dynamic memory
management");
printf("n1.create");
printf("n2.display");
printf("n3.insert an element in a list");
printf("n4.delete an element from list");
printf("n5.quit");
printf("nenter your chioce(1-5)");
scanf("%d",&choice);
switch(choice)
{
case 1:head=create();
break;
case 2:display(head);
break;
case 3:head=insert(head);
break;
case 4:dele(&head);

42. 42 | P a g e
break;
case 5:exit(0);
default:
printf("invalid choice,try again");
}
}
while(choice!=5);
}
node* create()
{
node *temp,*New,*head;
int val,flag;
char ans='y';
node *get_node();
temp=NULL;
flag=TRUE;
do
{
printf("n enter the element:");
scanf("%d",&val);
New=get_node();
if(New==NULL)
printf("nmemory is not allocated");
New->data=val;
if(flag==TRUE)
{
head=New;
temp=head;
flag=FALSE;
}
else
{
temp->next=New;
temp=New;
}
printf("ndo you want to enter more elements?(y/n)");
}
while(ans=='y');
printf("nthe list is createdn");
return head;
}
node *get_node()
{
node *temp;
temp=(node*)malloc(sizeof(node));
temp->next=NULL;
return temp;
}
void display(node *head)
{

43. 43 | P a g e
node *temp;
temp=head;
if(temp==NULL)
{
printf("nthe list is emptyn");
return;
}
while(temp!=NULL)
{
printf("%d->",temp->data);
temp=temp->next;
}
printf("NULL");
}
node *search(node *head,int key)
{
node *temp;
int found;
temp=head;
if(temp==NULL)
{
printf("the linked list is emptyn");
return NULL;
}
found=FALSE;
while(temp!=NULL && found==FALSE)
{
if(temp->data!=key)
temp=temp->next;
else
found=TRUE;
}
if(found==TRUE)
{
printf("nthe element is present in the listn");
return temp;
}
else
{
printf("the element is not present in the listn");
return NULL;
}
}
node *insert(node *head)
{
int choice;
node *insert_head(node *);
void insert_after(node *);
void insert_last(node *);
printf("n1.insert a node as a head node");

44. 44 | P a g e
printf("n2.insert a node as a head node");
printf("n3.insert a node at intermediate position in t6he list");
printf("nenter your choice for insertion of node:");
scanf("%d",&choice);
switch(choice)
{
case 1:head=insert_head(head);
break;
case 2:insert_last(head);
break;
case 3:insert_after(head);
break;
}
return head;
}
node *insert_head(node *head)
{
node *New,*temp;
New=get_node();
printf("nEnter the element which you want to insert");
scanf("%d",&New->data);
if(head==NULL)
head=New;
else
{
temp=head;
New->next=temp;
head=New;
}
return head;
}
void insert_last(node *head)
{
node *New,*temp;
New=get_node();
printf("nenter the element which you want to insert");
scanf("%d",&New->data);
if(head==NULL)
head=New;
else
{
temp=head;
while(temp->next!=NULL)
temp=temp->next;
temp->next=New;
New->next=NULL;
}
}
void insert_after(node *head)
{

45. 45 | P a g e
int key;
node *New,*temp;
New=get_node();
printf("nenter the elements which you want to insert");
scanf("%d",&New->data);
if(head==NULL)
{
head=New;
}
else
{
printf("enter the element which you want to insert the node");
scanf("%d",&key);
temp=head;
do
{
if(temp->data==key)
{
New->next-temp->next;
temp->next=New;
return;
}
else
temp=temp->next;
}
while(temp!=NULL);
}
}
node *get_prev(node *head,intval)
{
node *temp,*prev;
int flag;
temp=head;
if(temp==NULL)
return NULL;
flag=FALSE;
prev=NULL;
while(temp!=NULL && ! flag)
{
if(temp->data!=val)
{
prev=temp;
temp=temp->next;
}
else
flag=TRUE;
}
if(flag)
return prev;
else

46. 46 | P a g e
return NULL;
}
void dele(node **head)
{
node *temp,*prev;
int key;
temp=*head;
if(temp==NULL)
{
printf("nthe list is emptyn");
return;
}
printf("nenter the element you want to delete:");
scanf("%d",&key);
temp=search(*head,key);
if(temp!=NULL)
{
prev=get_prev(*head,key);
if(prev!=NULL)
{
prev->next=temp->next;
free(temp);
}
else
{
*head=temp->next;
free(temp);
}
printf("nthe element is deletedn");
}
}