德尔福记录 [英] Records in Delphi

问题描述

关于Delphi中的记录的一些问题：

1. 由于记录几乎像类，为什么不使用类而不是记录？ li>
   
2. 从理论上讲，当记录由变量声明时被分配给记录;但是，如何释放内存？


3. 我可以理解指针到记录列表对象中的效用，但是可以使用泛型容器（ TList ），有没有需要使用指针呢？如果没有，如何删除/释放每个记录到通用容器？如果我想删除一个特定的记录到一个通用容器，怎么办？

解决方案

对于1和2：记录是值类型，而类是引用类型。它们分配在堆栈上，或者直接在包含它们的任何较大变量的内存空间中，而不是通过指针分配，并在编译器超出范围时自动清除。

对于您的第三个问题， TList< TMyRecord> 内部声明一个数组TMyRecord 用于存储空间。列表中的所有记录将被清除。如果要删除特定的一个，请使用删除方法按索引删除，或使用删除方法来查找并删除。但是请注意，由于它是一种价值类型，所做的一切都将制作记录副本，而不是复制其引用。

some questions about records in Delphi:

1. As records are almost like classes, why not use only classes instead of records?
2. In theory, memory is allocated for a record when it is declared by a variable; but, and how is memory released after?
3. I can understand the utility of pointers to records into a list object, but with Generics Containers (TList<T>), are there need to use pointer yet? if not, how to delete/release each record into a Generic Container? If I wanna delete a specific record into a Generic Container, how to do it?

解决方案

For 1 and 2: records are value types, while classes are reference types. They're allocated on the stack, or directly in the memory space of any larger variable that contains them, instead of through a pointer, and automatically cleaned up by the compiler when they go out of scope.

As for your third question, a TList<TMyRecord> internally declares an array of TMyRecord for storage space. All the records in it will be cleaned up when the list is destroyed. If you want to delete a specific one, use the Delete method to delete by index, or the Remove method to find and delete. But be aware that since it's a value type, everything you do will be making copies of the record, not copying references to it.

这篇关于德尔福记录的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！