Program 115:Binary Search using Recurion

Program 115:
 

Method I:Passing array to function as pointer

#include<stdio.h>
void sort(int ,int *);
void binarysearch(int ,int ,int *,int);
main()
{
 int i,n,searchno;
 printf("Enter size of array\n");
 scanf("%d",&n);
 int a[n];
    printf("Enter the numbers in sorted order\n");
    for(i=0;i<n;i++)
    {
     scanf("%d",&a[i]);
    }
    
     sort(n,&a[0]);
     
     printf("Sorted array is\n");
     

     for(i=0;i<n;i++)
    {
     printf("%d\n",a[i]);
    }
    printf("Enter element to be searched\n");
    scanf("%d",&searchno);
 binarysearch(1,n,&a[0],searchno);
    
}

void sort(int n,int *a)
{
 int i,j,temp;
 for(i=0;i<n;i++)//for sorting in ascending order
    {
     for(j=i+1;j<n;j++)
 {
  if(a[i]>a[j])
  {
   temp=a[i];
   a[i]=a[j];
   a[j]=temp;
  }
 }
    }
}

void binarysearch(int low,int high,int *a,int searchno)
{
 int mid;
 if(low>high)
 {
     printf("Search is not successful\n");
  return;
 }
 mid=(low+high)/2;
 if(a[mid]==searchno)
 {
  printf("Search successful\n");
  return;
 }
 
 else if(searchno<a[mid])
 {
  binarysearch(low,mid-1,a,searchno);
 }
 else if(searchno>a[mid])
 {
  binarysearch(mid+1,high,a,searchno);
 }

}

Method II: Passing array to function


#include<stdio.h>
void sort(int n,int a[]);
void binarysearch(int low,int high,int a[],int searchno);
main()
{
 int i,n,searchno;
 printf("Enter size of array\n");
 scanf("%d",&n);
 int a[n-1];
    printf("Enter the numbers in sorted order\n");
    for(i=0;i<n;i++)
    {
     scanf("%d",&a[i]);
    }
    
     sort(n,a);
     
     printf("Sorted array is\n");
     

     for(i=0;i<n;i++)
    {
     printf("%d\n",a[i]);
    }
    printf("Enter element to be searched\n");
    scanf("%d",&searchno);
 binarysearch(1,n,a,searchno);
    
}

void sort(int n,int a[])
{
 int i,j,temp;
 for(i=0;i<n;i++)//for sorting in ascending order
    {
     for(j=i+1;j<n;j++)
 {
  if(a[i]>a[j])
  {
   temp=a[i];
   a[i]=a[j];
   a[j]=temp;
  }
 }
    }
}

void binarysearch(int low,int high,int a[],int searchno)
{
 int mid;
 if(low>high)
 {
     printf("Search is not successful\n");
  return;
 }
 mid=(low+high)/2;
 if(a[mid]==searchno)
 {
  printf("Search successful\n");
  return;
 }
 
 else if(searchno<a[mid])
 {
  binarysearch(low,mid-1,a,searchno);
 }
 else if(searchno>a[mid])
 {
  binarysearch(mid+1,high,a,searchno);
 }

}

Explanation:

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 Output: