Robin Chow's C++ Blog

[導入]More Exceptional C++ 之 17（待翻譯）

使用宏時須注意：

1. 參數兩邊要加括號
2. 整個表達式兩邊要加括號
3. 特別注意表達式多次求值的情況，如 max(++i, j)
4. 宏會攪亂名字空間
5. 宏不能遞歸
6. 宏沒有地址
7. 宏不利于調試
   

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.

文章來源:http://my.donews.com/robinchow/2007/02/11/bavcdirqeacybkdedpxorhuddpwyehtghojl/

posted on 2007-10-23 20:47 Robin Chow 閱讀(97) 評論(0)  編輯 收藏 引用