Question

c语言 at 前后下划线

比如：volatile unsigned char xdata ram[offset] _at_ Ram_base;
对了，我的疑问在于：这个_at_有没有什么相关知识点？麻烦给讲解一下，谢谢。

Answer 1

嵌入式C的关键字，变量可能定位在绝对内存地址
——————————————————
The absolute address following the _at_ keyword must conform to the
physical boundaries of the memory space for the variable. The Cx51 Compiler
checks for and reports invalid address specifications.
The following restrictions apply to absolute variable location using the _at_ keyword:
Absolute variables cannot be initialized.
Functions may not be located at an absolute address.
Bit variables may not be located at an absolute address.

在_at_后面的绝对地址要符合内存空间的物理边界
不能被初始化
函数和位变量不能定位在绝对地址

Answer 2

c语言中打下划线和平时一样，在英文状态(英文输入法)下同时按住“shift
+　－”（shift和减号）即可。