C Program for the Implementation of a Symbol Table with functions to CREATE, INSERT, MODIFY, SEARCH and DISPLAY | CS1207 - System Software Laboratory

AIM:
         To write a "C" program for the implementation of symbol table with functions to create, insert, modify, search and display in CS1207 - System Software Lab.

SOURCE CODE:
#include<stdio.h>
#include<conio.h>
#include<alloc.h>
#include<string.h>
#include<stdlib.h>
#define NULL 0
int size=0;
void Insert();
void Display();
void Delete();
int Search(char lab[]);
void Modify();
struct SymbTab
{
char label[10],symbol[10];
int addr;
struct SymbTab *next;};
struct SymbTab *first,*last;
void main()
{
int op,y;
char la[10];
clrscr();
do
{
printf("\n\tSYMBOL TABLE IMPLEMENTATION\n");
printf("\n\t1.INSERT\n\t2.DISPLAY\n\t3.DELETE\n\t4.SEARCH\n\t5.MODIFY\n\t6.END\n");
printf("\n\tEnter your option : ");
scanf("%d",&op);
switch(op)
{
   case 1:
      Insert();
      break;
   case 2:
      Display();
      break;
   case 3:
      Delete();
      break;
   case 4:
      printf("\n\tEnter the label to be searched : ");
      scanf("%s",la);
      y=Search(la);
      printf("\n\tSearch Result:");
      if(y==1)
    printf("\n\tThe label is present in the symbol table\n");
      else
    printf("\n\tThe label is not present in the symbol table\n");
      break;
   case 5:
      Modify();
      break;
   case 6:
      exit(0);
}
}while(op<6);
getch();
}
void Insert()
{
int n;
char l[10];
printf("\n\tEnter the label : ");
scanf("%s",l);
n=Search(l);
if(n==1)
   printf("\n\tThe label exists already in the symbol table\n\tDuplicate can't be inserted");
else
   {
    struct SymbTab *p;
    p=malloc(sizeof(struct SymbTab));
    strcpy(p->label,l);
    printf("\n\tEnter the symbol : ");
    scanf("%s",p->symbol);
    printf("\n\tEnter the address : ");
    scanf("%d",&p->addr);
    p->next=NULL;
    if(size==0)
     {
      first=p;
      last=p;
     }
    else
     {
      last->next=p;
      last=p;
     }
    size++;
   }
   printf("\n\tLabel inserted\n");
}
void Display()
{
int i;
struct SymbTab *p;
p=first;
printf("\n\tLABEL\t\tSYMBOL\t\tADDRESS\n");
for(i=0;i<size;i++)
   {
    printf("\t%s\t\t%s\t\t%d\n",p->label,p->symbol,p->addr);
    p=p->next;
   }
}
int Search(char lab[])
{
int i,flag=0;
struct SymbTab *p;
p=first;
for(i=0;i<size;i++)
   {
    if(strcmp(p->label,lab)==0)
     flag=1;
    p=p->next;
   }
return flag;
}
void Modify()
{
char l[10],nl[10];
int add,choice,i,s;
struct SymbTab *p;
p=first;
printf("\n\tWhat do you want to modify?\n");
printf("\n\t1.Only the label\n\t2.Only the address\n\t3.Both the label and address\n");
printf("\tEnter your choice : ");
scanf("%d",&choice);
switch(choice)
   {
     case 1:
       printf("\n\tEnter the old label : ");
       scanf("%s",l);
       s=Search(l);
       if(s==0)
    printf("\n\tLabel not found\n");
       else
    {
    printf("\n\tEnter the new label : ");
    scanf("%s",nl);
    for(i=0;i<size;i++)
    {
       if(strcmp(p->label,l)==0)
         strcpy(p->label,nl);
       p=p->next;
    }
    printf("\n\tAfter Modification:\n");
    Display();
    }
    break;
    case 2:
       printf("\n\tEnter the label where the address is to be modified : ");
       scanf("%s",l);
       s=Search(l);
       if(s==0)
    printf("\n\tLabel not found\n");
       else
    {
    printf("\n\tEnter the new address : ");
    scanf("%d",&add);
    for(i=0;i<size;i++)
    {
       if(strcmp(p->label,l)==0)
        p->addr=add;
       p=p->next;
    }
    printf("\n\tAfter Modification:\n");
    Display();
    }
    break;
    case 3:
       printf("\n\tEnter the old label : ");
       scanf("%s",l);
       s=Search(l);
       if(s==0)
    printf("\n\tLabel not found\n");
       else
    {
    printf("\n\tEnter the new label : ");
    scanf("%s",nl);
    printf("\n\tEnter the new address : ");
    scanf("%d",&add);
     for(i=0;i<size;i++)
    {
       if(strcmp(p->label,l)==0)
        {
         strcpy(p->label,nl);
         p->addr=add;
        }
       p=p->next;
    }
    printf("\n\tAfter Modification:\n");
    Display();
    }
    break;
    }
}
void Delete()
{
int a;
char l[10];
struct SymbTab *p,*q;
p=first;
printf("\n\tEnter the label to be deleted : ");
scanf("%s",l);
a=Search(l);
if(a==0)
    printf("\n\tLabel not found\n");
else
   {
    if(strcmp(first->label,l)==0)
    first=first->next;
    else if(strcmp(last->label,l)==0)
     {
      q=p->next;
      while(strcmp(q->label,l)!=0)
      {
       p=p->next;
       q=q->next;
      }
      p->next=NULL;
      last=p;
     }
    else
     {
      q=p->next;
      while(strcmp(q->label,l)!=0)
      {
       p=p->next;
       q=q->next;
      }
      p->next=q->next;
    }
    size--;
    printf("\n\tAfter Deletion:\n");
    Display();
   }
}

OUTPUT:

INSERTION:

DISPLAY:

DELETION:

SEARCH:

MODIFICATION:

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