BINARY SEARCH

It is a Different type of Search in which we divide the array into Two Parts from the middle element. (The array Must be sorted before we do this)

• Step 1: First divide the array of elements in half.
• Step 2: In the second step we compare the target value with the middle element of the array. If it matches the middle element then search ends here and doesn’t proceed further.
• Step 3: Else if the element less than the middle element then we begin the search in lower half of the array.
• Step 4: Else if the element is greater than the middle element then we begin the search in greater half of the array.
• Step 5: We will repeat the steps 3 ,4 and 5 until our target element is found.

So That's Simple Now

#include<iostream>
 
using namespace std;
 
int main()
{
    int search(int [],int,int);
    int n,i,a[100],e,res;
    cout<<"How Many Elements:";
    cin>>n;
    cout<<"\nEnter Elements of Array in Ascending order\n";
    
    for(i=0;i<n;++i)
    {
        cin>>a[i];
    }
    
    cout<<"\nEnter element to search:";
    cin>>e;
    
    res=search(a,n,e);
    
    if(res!=-1)
        cout<<"\nElement found at position "<<res+1;
    else
        cout<<"\nElement is not found....!!!";
 
    return 0;
}
 
int search(int a[],int n,int e)
{
    int f,l,m;
    f=0;
    l=n-1;
    
    while(f<=l)
    {
        m=(f+l)/2;
        if(e==a[m])
            return(m);
        else
            if(e>a[m])
                f=m+1;
            else
                l=m-1;
    }
    
    return -1;
}