BINARY SEARCH ALGORITHM

/* Binary search using Structures */

#include<stdio.h>
#include<conio.h>
#include<alloc.h>
void main()
 {
  struct students
  {
   int rno,pno;
   char name[100];
  };

   int n,i,j,r,t,low,mid,high;

   struct students info[100];
   clrscr();

   printf("\n\n How many students : ");
   scanf("%d",&n);

   if(n<=0 || n>100)
   {
    printf("\n\n Enter a valid digit between 1 & 100");
    getch();
    exit(0);
   }

   for(i=0;i<n;i++)
   {
     printf("\n\n Enter the name of %d student : ",i+1);
     scanf("%s",info[i].name);

     printf("\n\n His roll numbers : ");
     scanf("%d",&info[i].rno);

     printf("\n\n His phone numbers : ");
     scanf("%d",&info[i].pno);
   }

   printf("\n\n\n Name \t\t Roll no \t\t Phone no");

   for(i=0;i<n;i++)
   {
     printf("\n\n %s \t\t %d \t\t\t %d",info[i].name,info[i].rno,info[i].pno);
   }


   printf("\n\n Enter the roll no to be searched : ");
   scanf("%d",&r);

   for(i=0;i<n;i++)
   for(j=0;j<n-1-i;j++)
   {
     if(info[j].rno > info[j+1].rno)
     {
      t = info[j].rno;
      info[j].rno = info[j+1].rno;
      info[j+1].rno = t;
     }
   }

   low = 1; high = n;

   do{
      mid = (low + high)/2;

      if(r>info[mid].rno)
      low = mid + 1;

      else if(r<info[mid].rno)
      high = mid - 1;
     }
      while( r!=info[mid].rno && low<=high);

      if(r==info[mid].rno)
      printf("\n\n The roll number %d is found",r);

      else
      printf("\n\n The roll number %d is not found",r);


    getch();

 }