Dragon Book DX9 Chapter5 Light Creation and getasynckeystate () &0x8000f issues

Note 1: When we find a text, press the physical button a AAAAA, you will find that the first time there will be a partition.

Reference:http://tieba.baidu.com/p/1829831956

How does the return value of Getasynckeystate () understand?

The instance code has the IF (:: Getasynckeystate (vk_right) & 0x8000f) This sentence, press the → Key to get 0x1

void Main () {    staticint testint=0;      while (1)    {        if( short a =(:: Getasynckeystate (Vk_right)))//        {        cout< <a<<Endl;              cout<<testInt++<<" times "<<Endl;     }}}

The above code results found that-32767 appeared once.

if (Short a = (:: Getasynckeystate (Vk_right)) &0x8000f), press output only once 1

Where short negative numbers are stored in the form of a complement to the computer, 32767 is 0x8001-32768 for 0x8000

Summary: 1. When we continue to press the key not to release, use Getasynckeystate (vk_right)) &0x8000f) only return once true; 2. 0X8000F where the starting 8 does not work

Dragon Book DX9 Chapter5 Light Creation and getasynckeystate () &0x8000f issues