Interview Questions

The Singleton design pattern ensures a class only has one instance, and provides a global point of access to it. The class keeps track of its sole instance and ensures that no other instance can be created. Singleton classes are appropriate for situations where it makes sense for a single object to provide access to a global resource.Several Cocoa framework classes are singletons. They includeNSFileManager, NSWorkspace, NSApplication, and, in UIKit,UIApplication. A process is limited to one instance of these classes. When a client asks the class for an instance, it gets a shared instance, which is lazily created upon the first request.

IUnknown as an interface of a COM object. Every COM object has to support IUnknown, besides optionally adding other interfaces.

IUnknown is made of QueryInterface, AddRef and Release.

Profitability control is a mechanism of monitoring the sales made, profits earned and expenditure incurred by a company. The relative profit earning capacity of a firm’s products and consumer groups can be determined via profitability control. Sometimes surpisingly, it may be found out by companies how a small proportion of their products and even customers actually account for a significant percentage of the company’s profits. This can be achieved through profitability control. At times when the companies earn surplus profits, then such profits may even be ploughed back or reinvested. This also forms part of profitability control.

- %FOUND

 This is a Boolean variable which evaluates to TRUE if the last row is successfully fetched.

- %NOTFOUND

 This is a Boolean variable which evaluates to TRUE if the last row is not successfully fetched. This means there are no more rows to fetch.

- %ROWCOUNT

 Returns the number of rows fetched by the cursor.

- %ISOPEN

If the cursor is open, it evaluates to TRUE else FALSE.

If you mark an instance variable as transient, you're telling the JVM to skip (ignore) this variable when you attempt to serialize the object containing it.

One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.

Some of the rules which should be followed while naming a variable in VB are as follows: 

1) Characters should be less than 255.

2) Space between characters should be allowed.

3) A variable should begin with a number.

4) Period may not be permitted.