BinarySearch

//srishti1302
#include <stdio.h>
#define COMPARE(x,y) ( (x)<(y)?-1:(x)==(y)? 0 :1 )
int binsearch(int a[20],int k,int left,int right)
{

    if(left<right)
    {
        int middle=(left+right)/2;
        switch(COMPARE(a[middle],k))
        {
            case -1: return binsearch(a,k,middle+1,right);
                     break;

            case 0: return middle;
                    break;

            case 1: return binsearch(a,k,left,middle-1);
                    break;
        }
    }
    return -1;
}
int main()
{
    int n,a[20],k,res;
    printf("Enter size of the array: ");
    scanf("%d",&n);
    printf("\nEnter the array elements:\n");
    for(int i=0;i<n;i++)
        scanf("%d",&a[i]);
    printf("\nEnter the number to be searched:\n");
    scanf("%d",&k);

    res=binsearch(a,k,0,n-1);
    if(res==-1)
        printf("Element not found!!");
    else
        printf("\nThe number %d is found at positon %d in the given list",k,res+1);

    return 0;
}