binary search in C# goes in an infinite loop

Question

2.00/5 (1 vote)

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Hi i am implementing binary search in c#, here is the code

C#

int[] a={1,3,4,5,7,9,10};
int max=6;
int min=0;
int target=1;
while(max>=min)
{
    if((max+min)!=0)
    {
    int mid=(max+min)/2;
    if(a[mid]==target)
    {
        Console.Write(a[mid]);
        min=max;
    }
        else if(a[mid]>target)
        max=mid-1;
        else
        min=mid+1;
    }
    else
    Console.Write(a[max]);
    }

but it is going in infinite loop, the code works fine if I remov = in while(max>=min) but it won't check for starting min and max value although if I set target equal to anything anything but extreme values, it gives true result. what can I do?

Posted 28-Sep-14 17:03pm

suleman115

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Comments

Sergey Alexandrovich Kryukov 29-Sep-14 1:45am

Always use the debugger, you will see what's going on.
—SA

2 solutions

Solution 1

Try removing equal from

C#

while(max>=min)

So change

C#

while(max>=min)

to

C#

while(max>min)

Posted 28-Sep-14 18:30pm

gopesh2010

Comments

suleman115 29-Sep-14 1:31am

well i mentioned in the question that when i remove =, program works fine, but we need = to check for the values at index 0 and 6 that is min and max..then what?

gopesh2010 29-Sep-14 1:40am

First of all if max is equal to min it will always go to infinite loop, secondly before going inside your loop you can check that the value you are going to search is at location min or max, that will save the overhead of a loop.

suleman115 29-Sep-14 1:54am

got the point about min=max, thank you

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suleman115 · Accepted Answer · 2014-09-28T19:55:00

I should just make the min=max+1 when i find target, here:

C#

int[] a={1,3,4,5,7,9,10};
int max=6;
int min=0;
int target=1;
while(max>=min)
{
    int mid=(max+min)/2;
    if(a[mid]==target)
    {
        Console.Write(a[mid]);
        min=max+1;
    }
        else if(a[mid]>target)
        max=mid-1;
        else
        min=mid+1;
    }