TONT 41713 WPARAM和LPARAM中的W和L是什么意思？

历史的点滴。

原文链接：https://blogs.msdn.microsoft.com/oldnewthing/20031125-00/?p=41713

Once upon a time, Windows was 16-bit. Each message could carry with it two pieces of data, called WPARAM and LPARAM. The first one was a 16-bit value (“word”), so it was called W. The second one was a 32-bit value (“long”), so it was called L.

从前的时候，Windows是16位的，每条系统消息可以承载两则数据，分别被称为WPARAM和LPARAM。前者是一个16位的值（即所谓的『字』），所以是W开头的（Word）。后者是一个32位的值（长整形），所以是L开头的（Long）。

You used the W parameter to pass things like handles and integers. You used the L parameter to pass pointers.

开发人员可以用W参数传递句柄和整型类数据，用L参数传递指针。

When Windows was converted to 32-bit, the WPARAM parameter grew to a 32-bit value as well. So even though the “W” stands for “word”, it isn’t a word any more. (And in 64-bit Windows, both parameters are 64-bit values!)

后来Windows进入了32位时代，WPARAM参数也进化为了一个32位的值，所以尽管W代表『字』（Word），WPARAM也不再是一个『字』了。（何况在64位Windows中，两个参数还都进化成64位了呢！）

It is helpful to understand the origin of the terms. If you look at the design of window messages, you will see that if the message takes a pointer, the pointer is usually passed in the LPARAM, whereas if the message takes a handle or an integer, then it is passed in the WPARAM. (And if a message takes both, the integer goes in the WPARAM and the pointer goes in the LPARAM.)

了解这些术语的起源很有帮助。观察一下窗体消息的的设计，你就会发现如果消息接受指针的话，指针通常在LPARAM中进行传递，而对于接受句柄或整型的消息，那么数据通常会传入WPARAM。（如果是同时接受两个参数的，那么整型传入WPARAM，指针传入LPARAM。）

Once you learn this, it makes remembering the parameters for window messages a little easier. Conversely, if a message breaks this rule, then it sort of makes your brain say, “No, that’s not right.”

对此有所了解后，对于记住窗体消息的参数（应该传入哪类数据）就简单一点了。反之，如果某条消息传入的参数不符合以上规则，那么你潜意识里可能就会觉得：『噢，好像有点不对劲。』