/* Lab program no. 1*/
#include<stdio.h>
#include<process.h>
#include<stdlib.h>
#include<string.h>
struct student
   {
   int usn;
   char name[20];
   int marks1,marks2,marks3;
   };
typedef struct student STD;
/*function to search for USN*/
int search_record(int key_usn,FILE *fp)
  {
  STD st;
  /*while not end of file*/
  for(;;)
   {
   if((fscanf(fp,"%d%s%d%d%d",&st.usn,st.name,&st.marks1,&st.marks2,&st.marks3))==EOF)
    break;
   if(key_usn==st.usn)
     {
     printf("USN\tName\tMarks1\tMarks2\tMarks3\n");
     printf(" %d\t%s\t%d\t%dt%d",st.usn,st.name,st.marks1,st.marks2,st.marks3);
     return 1;
     }
   }
   return 0;
  }
void append_record(FILE *fp)
  {
   STD st;
   printf("USN   :");scanf("%d",&st.usn);
   printf("Name  :");scanf("%s",st.name);
   printf("Marks1:");scanf("%d",&st.marks1);
   printf("Marks2:");scanf("%d",&st.marks2);
   printf("Marks3:");scanf("%d",&st.marks3);
   fprintf(fp,"%d %s %d %d %d\n",st.usn,st.name,st.marks1,st.marks2,st.marks3);
  }
void display_record(FILE *fp)
  {
  STD st;
  printf("USN\tName\tMarks1\tMarks2\tMarks3\n");
  for(;;)
   {
  if((fscanf(fp,"%d%s%d%d%d",&st.usn,st.name,&st.marks1,&st.marks2,&st.marks3))==EOF)
   break;
   printf("%d\t%s\t%d\t%d\t%d\n",st.usn,st.name,st.marks1,st.marks2,st.marks3);

   }
  }
void main()
   {
   STD st;
   char fname[10];
   FILE *fp;
   int key_usn,choice,flag=0;
   printf("Enter the file name\n");
   scanf("%s",fname);
   for(;;)
    {
    printf("1:Insert Record\n2:Search Record\n3:Display Record\n4:Exit");
    printf("\nEnter choice:");scanf("%d",&choice);
    switch(choice)
     {
      case 1:
	     fp=fopen(fname,"a+");
	     if(fp==NULL)
	      {
	       printf("Fopen failed\n");
	       break;
	      }
	      append_record(fp);
	      fclose(fp);
	      break;
       case 2:
	     fp=fopen(fname,"r");
	     if(fp==NULL)
	      {
	       printf("File open failed\n");
	       break;
	     }
	     printf("Enter USN :");
	     scanf("%d",&key_usn);
	     flag=search_record(key_usn,fp);
	     if(flag==0)
		 printf("The record is not present");
	     fclose(fp);
	     break;
	case 3:
	       fp=fopen(fname,"r");
	       if(fp==NULL)
		{
		 printf("File opened failed \n");
		 break;
		}
	      display_record(fp);
	      fclose(fp);
	      break;
	default:
		exit(0);
	}
     }
   }