C語言 - gcc: error: macro names must be identifiers

這個錯誤是指說當code中使用 #ifdef XXX 時 XXX不可以為數字開頭

The #ifdef directive is used to check if a pre-processor symbol is defined. The standard (C11 6.4.2 Identifiers) mandates that identifiers must not start with a digit.

ex.
#ifdef 123_SUPPORT ->  /* error!!! */
.
.
.
#endif

正確的：

#ifdef TEST_123_SUPPORT -> /* ok!!!! */
.
.
.
#endif

Reference:

http://stackoverflow.com/questions/426736/error-macro-names-must-be-identifiers-using-ifdef-0