main.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void add_item();
void read_item();
void modify_item();
void delete_item();
int option();
void displayheading();
struct phonebook
      {
            char name[30];
            long int pno;
            char address[30];
      };
void main()
{
      int c;
      char con='Y';
      while(con=='Y')
      {
            c=option();
            switch(c)
            {
                  case 1:
                  add_item();
                  break;
                  case 2:
                  read_item();
                  break;
                  case 3:
                  modify_item();
                  break;
                  case 4:
                  delete_item();
                  break;
            }
            printf("\nType 'Y' to continue with operations:");
            scanf("\n%c",&con);
      }
}
int option()
{
      int ch;
      printf("\nOptions available:");
      printf("\n1 to add contact in phonebook \n2 to read a contact from phonebook \n3 to modify contacts \n4 to delete a contact from the phonebook");
      printf("\nEnter choice: ");
      scanf("%d",&ch);
      return ch;
}
void add_item()
{
      struct phonebook item;
      FILE *ft;
      char x='Y';
      ft=fopen("phonebook","a+");
      do
      {
            char ch;
            printf("\nEnter Name: ");
            scanf("%s",item.name);
            printf("\nEnter Phone Number: ");
            scanf("%ld",&item.pno);
            printf("\nEnter Email address: ");
            scanf("%s",item.address);
            fprintf(ft,"%s    %ld    %s\n",item.name,item.pno,item.address);
            printf("Type 'Y' to repeat the operation\n");
            scanf("\n%c",&ch);
            x=ch;
      }while(x=='Y');
      fclose(ft);
}
void read_item()
{
      struct phonebook item;
      FILE *ft;
      ft=fopen("phonebook","r");

      while(feof(ft)==0)
      {
            fscanf(ft,"%s     %ld     %s\n",item.name,&item.pno,item.address);
            printf("\n%s      %ld    %s",item.name,&item.pno,item.address);
      }
      fclose(ft);
}
void modify_item()
{
      struct phonebook item;
      FILE *ft,*fp;
      ft=fopen("phonebook","r");
      fp=fopen("temp","w+");
      long int pno,npno;
      printf("\nEnter the phone number which is to be modified and add the new phone number: \n");
      scanf("%ld %ld",&pno,&npno);
      while(!feof(ft))
      {
            fscanf(ft,"%s     %ld     %s\n",item.name,&item.pno,item.address);
            if(item.pno!=pno)
            fprintf(fp,"%s    %ld    %s\n",item.name,item.pno,item.address);
            else
            {
                  item.pno=npno;
                  fprintf(fp,"%s    %ld    %s\n",item.name,item.pno,item.address);
            }
      }
      fclose(ft);
      fclose(fp);
      remove("phonebook");
      rename("temp","phonebook");
}
void delete_item()
{
      struct phonebook item;
      FILE *ft,*fp;
      long int pno;
      ft=fopen("phonebook","r");
      fp=fopen("temp","w+");
      printf("\nEnter the phone number to be deleted: \n");
      scanf("%ld",&pno);
      while (!feof(ft))
      {
            fscanf(ft,"%s     %ld     %s\n",item.name,&item.pno,item.address);
            if(pno!=item.pno)
            fprintf(fp,"%s    %ld    %s\n",item.name,item.pno,item.address);
      }
      fclose(ft);
      fclose(fp);
      remove("phonebook");
      rename("temp","phonebook");
}