How to judge the existence of a value and a Range

Wchar wcvalue;

How can we determine that wcvalue is one of the ten numbers 0-9?

Many people will write: If (wcvalue> = 0x30 & wcvalue <= 0x39)

Very intuitive, but a little ugly.

In fact, you can change it:

If (wcValue-0x30 <0x10)

However, a problem occurs. Wcvalue is treated as a number as a signed number. If wcvalue is smaller than 0x30, the calculation result is considered as a negative number. To solve this problem, you only need to forcibly convert it to the DWORD type. In this way, negative numbers are considered as a very huge positive integer. (Here, we should look at the complement knowledge)

Therefore, it is written as follows:

If (DWORD) wcValue-0x30 <0x10)