The Nine

All Delphi versions since Delphi 2006 have an updated memory manager that is faster and more feature rich.

One of the nicest features of the "new" memory manager allows applications to register (and unregister) expected memory leaks, and optionallyreport unexpected memory leaks on program shutdown.

自从Delphi2006 版本开始，新版的IDE加入了内存泄露报告方法。  

When creating WIN32 applications with Delphi it is imperative to make sure that you free all the objects (memory) you create dynamically.Amemory (or resource) leakoccurs when the program loses the ability to free the memory it consumes.

内存泄露的原因主要是程序员的错误，当动态创建objects却没有在使用完毕后释放free的时候，内存泄露就发生了。

Memory leak detecting and reporting is set to false by default. To enable it, you need to set the global variableReportMemoryLeaksOnShutdown to TRUE.When the applications is closed, if there are unexpected memory leaks the application will display the "Unexpected Memory Leak" dialog box.

打开内存泄露检测选项后，当程序运行结束且存在内存泄露的时候，程序会显示内存泄露对话框。

The best place for the ReportMemoryLeaksOnShutdown would be in theprogram's source code (dpr)file.

放置ReportMemoryLeaksOnShutdown的最佳位置是程序的dpr文件中，例如：

Note:a global variableDebugHookis used above to make sure memory leaks are displayed when the application is run in debug mode - when you fit F9 from the Delphi IDE.

DebugHook 与 ReportMemoryLeaksOnShutdown 都是 System 下的变量。DebugHook: 程序中母体中运行时， 此值是 1； 独立运行时， 它是 0。在程序的任何地方加上一句 ReportMemoryLeaksOnShutdown := True;  这样程序在关闭时可检测是否有内存泄漏。如果这样使用：ReportMemoryLeaksOnShutdown := Boolean(DebugHook); 则程序只会在调试时报内存泄漏。

使用全局变量DebugHook的作用是确保程序在debug模式运行时显示内存泄露报告。但是注意在正常模式运行是不会报错的。

Test Drive: Memory Leak Detection
Having ReportMemoryLeaksOnShutdown set to TRUE, add the following code in the main form's OnCreate event handler.

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Run the application in debug mode, exit the application - you should see the memory leak dialog box.