.NET Tutorials, Forums, Interview Questions And Answers
Welcome :Guest
Sign In
Win Surprise Gifts!!!

Top 5 Contributors of the Month
Gaurav Pal

Home >> Interview Question >> ASP.Net >> Post New Question Subscribe to Interview Questions

What is the heap?

Posted By :Shashi Ray     Posted Date :October 10, 2008    Points :10   Category :ASP.Net 
The heap is where malloc(), calloc(), and realloc() get memory.

Getting memory from the heap is much slower than getting it from the stack. On the other hand, the heap is much more flexible than the stack. Memory can be allocated at any time and deallocated in any order. Such memory isn't deallocated automatically; you have to call free().
Recursive data structures are almost always implemented with memory from the heap. Strings often come from there too, especially strings that could be very long at runtime. If you can keep data in a local variable (and allocate it from the stack), your code will run faster than if you put the data on the heap. Sometimes you can use a better algorithm if you use the heap faster, or more robust, or more flexible. Its a tradeoff.
If memory is allocated from the heap, its available until the program ends. That's great if you remember to deallocate it when you're done. If you forget, it's a problem. A ?memory leak is some allocated memory that's no longer needed but isn't deallocated. If you have a memory leak inside a loop, you can use up all the memory on the heap and not be able to get any more. (When that happens, the allocation functions return a null pointer.) In some environments, if a program doesn't deallocate everything it allocated, memory stays unavailable even after the program ends.

You can also find related Interview Question to What is the heap?  below: 

Can I avoid using the garbage collected heap?

All languages that target the runtime allow you to allocate class objects from the garbage-collected heap. This brings benefits in terms of fast allocation, and avoids the need for programmers to work out when they should explicitly 'free' each object.
The CLR also provides what are called ValueTypes-these are like classes, except that ValueType objects are allocated on the runtime stack (rather than the heap), and therefore reclaimed automatically when your code exits the procedure in which they are defined. This is how "structs" in C# operate.

Managed Extensions to C++ lets you choose where class objects are allocated. If declared as managed Classes, with the __gc keyword, then they are allocated from the garbage-collected heap. If they don't include the __gc keyword, they behave like regular C++ objects, allocated from the C++ heap, and freed explicitly with the "free" method. (More...)

what is Stack and Heap?

stack is used to store variable data of fixed length.
stack is LIFO ie one the last item in stack is first served and also removed first.

Heap is used to store data whose size and length can only be determined at runtime and are subjected to change.
But a reference to that data is stored on the stack.

so anything in our Heap can be accessed at any time.


Quick Links For Interview Questions Categories:
ASP.Net Windows Application   .NET Framework   C#   VB.Net   ADO.Net  
Sql Server   SharePoint   Silverlight   OOPs   JQuery   JavaScript/VBScript
Biztalk Patten/Practices .IIS WCF WPF WWF
Networking Aptitude Others   All      

Find questions, FAQ's and their answers related to .NET, C#, Vb.Net, Sql Server and many more.

Now you can find lots of .NET, C#, Vb.Net, SQL Server,Windows, ASP.Net related Questions and their Answers here at www.dotnetspark.com. Our aim is to help you pass your certification Exams (MCP, MCSD, MCAD etc.,) with flying scores and get good name in your company.

So, Start looking our Interview Question section daily and improve your .NET Skills. You can also help others by posting Interview Questions and their Answers in this section.

Hall of Fame    Twitter   Terms of Service    Privacy Policy    Contact Us    Archives   Tell A Friend