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[导入]More Exceptional C++ 之 17（待翻译）

使用宏时须注意：

1. 参数两边要加括号
2. 整个表达式两边要加括号
3. 特别注意表达式多次求值的情况，如 max(++i, j)
4. 宏会搅乱名字空间
5. 宏不能递归
6. 宏没有地址
7. 宏不利于调试
   

On a compliant compiler, it is not possible for a macro to create any of the following:

• a trigraph (trigraphs are replaced in phase 1);

• a universal character name (\uXXXX, replaced in phase 1);

• an end-of-line line-splicing backslash (replaced in phase 2);

• a comment (replaced in phase 3);

• another macro or preprocessing directive (expanded and executed in phase 4); or

• changes to a character literal (for example, 'x') or string literal (for example, "hello, world") via macro names inside the strings.

文章来源:http://my.donews.com/robinchow/2007/02/11/bavcdirqeacybkdedpxorhuddpwyehtghojl/

posted on 2007-10-23 20:47 Robin Chow 阅读(86) 评论(0)  编辑 收藏 引用