C# in a nutshell pdf download

Customers where c. Name; return query. AsExpandable where c. Any purchaseCriteria. Compile select c. Using Expression Variables in Subqueries Suppose we want to write our previous example without using the Customer. ID where custPurchases. Any purchaseCriteria select c. Combining Expressions The AsExpandable wrapper also lets you write expressions that call other expressions. All you need to do is: Call Invoke to call the inner expression Call Expand on the final result. Invoke p p.

Contains "a" ; Console. WriteLine criteria2. Contains "a" Notice that we have a nice clean expression: the call to Invoke has been stripped away. Where criteria2. Contains "a" ; That last line recursively calls itself and the original predicate p. PredicateBuilder Click here for information on how to use PredicateBuilder. Core NuGet package. Click here to download the original LinqKit. NET Framework only Click here to download original source code and demo project. Enter and Monitor.

Invoke Parallel. For and Parallel. Offers a reference to key C programming concepts covering language elements, syntax, datatypes, and tasks.

When you have questions about C 7. When you have questions about C 8. NET Core, this best-selling guide has the answers you need. C is a language of. Covering the C programming language and C runtime library, this book is destined to be a constant companion in your work. This is a concise yet thorough reference to C 3. The remedy is to obtain an exclusive lock while reading and writing to the common field.

C provides the lock statement for just this purpose:. When two threads simultaneously contend a lock in this case, locker , one thread waits, or blocks , until the lock becomes available. Code that's protected in such a manner — from indeterminacy in a multithreading context — is called thread-safe. Shared data is the primary cause of complexity and obscure errors in multithreading. Although often essential, it pays to keep it as simple as possible.

You can include a timeout when calling Join , either in milliseconds or as a TimeSpan. It then returns true if the thread ended or false if it timed out. Sleep pauses the current thread for a specified period:. Framework 4. Yield method does the same thing — except that it relinquishes only to threads running on the same processor.

Sleep 0 or Yield is occasionally useful in production code for advanced performance tweaks. Yield anywhere in your code makes or breaks the program, you almost certainly have a bug. Query databases in a modern query language. Multithreading is managed internally by a thread scheduler, a function the CLR typically delegates to the operating system. A thread scheduler ensures all active threads are allocated appropriate execution time, and that threads that are waiting or blocked for instance, on an exclusive lock or on user input do not consume CPU time.

On a single-processor computer, a thread scheduler performs time-slicing — rapidly switching execution between each of the active threads. Under Windows, a time-slice is typically in the tens-of-milliseconds region — much larger than the CPU overhead in actually switching context between one thread and another which is typically in the few-microseconds region.

On a multi-processor computer, multithreading is implemented with a mixture of time-slicing and genuine concurrency, where different threads run code simultaneously on different CPUs. A thread is said to be preempted when its execution is interrupted due to an external factor such as time-slicing.

A thread is analogous to the operating system process in which your application runs. Just as processes run in parallel on a computer, threads run in parallel within a single process.

Processes are fully isolated from each other; threads have just a limited degree of isolation. In particular, threads share heap memory with other threads running in the same application. This, in part, is why threading is useful: one thread can fetch data in the background, for instance, while another thread can display the data as it arrives. With technologies such as ASP. NET and WCF, you may be unaware that multithreading is even taking place — unless you access shared data perhaps via static fields without appropriate locking , running afoul of thread safety.

Threads also come with strings attached. The biggest is that multithreading can increase complexity. This applies whether or not the interaction is intentional, and can cause long development cycles and an ongoing susceptibility to intermittent and nonreproducible bugs.

For this reason, it pays to keep interaction to a minimum, and to stick to simple and proven designs wherever possible. A good strategy is to encapsulate multithreading logic into reusable classes that can be independently examined and tested. The Framework itself offers many higher-level threading constructs, which we cover later. Multithreading will not always speed up your application — it can even slow it down if used excessively or inappropriately.

Calling Start on the thread then sets it running. The thread continues until its method returns, at which point the thread ends.

In this example, thread t executes Go — at much the same time the main thread calls Go. The result is two near-instant hellos. A thread can be created more conveniently by specifying just a method group — and allowing C to infer the ThreadStart delegate:.

With this approach, you can pass in any number of arguments to the method. You can even wrap the entire implementation in a multi-statement lambda:. The limitation of ParameterizedThreadStart is that it accepts only one argument. As we saw, a lambda expression is the most powerful way to pass data to a thread. However, you must be careful about accidentally modifying captured variables after starting the thread, because these variables are shared.

For instance, consider the following:. Therefore, each thread calls Console. Write on a variable whose value may change as it is running! The problem is less about multithreading and more about C 's rules for capturing variables which are somewhat undesirable in the case of for and foreach loops. Variable temp is now local to each loop iteration. We can illustrate the problem in the earlier code more simply with the following example:.

Because both lambda expressions capture the same text variable, t2 is printed twice:. Each thread has a Name property that you can set for the benefit of debugging. The static Thread.

CurrentThread property gives you the currently executing thread. By default, threads you create explicitly are foreground threads.