FORMRL 发表于 2017-10-24 12:05
可是如果我要定义#define A 2 ，这样的话，要怎么写？我试过A=2，A：2，A 2，都不对

help里面有示例

Keil EC++ Compiler
Preprocessor Symbols
Define sets preprocessor symbols, which can be checked with #if, #ifdef and #ifndef. The defined names are case-sensitive. Optionally, each name can have a value. Define: Check, NoExtRam, X1=1+5 is identical to the following C preprocessor #define statements:
#define Check
#define NoExtRam
#define X1 1+5

Undefine clears previous Define assignments that are entered in the options dialog of a higher Target or Group level.