紅線的生存日誌

1. (error) unresolved symbols

Apply new function in gpio.c to main.c

Have below error:

(error) unresolved symbols: 1
 _GPIO_init_output      from main.c.1.o

This error often means that some function has a declaration, but not a definition.

The issue could be that you are including a header file, which brings in some function declarations, but you either:

1. do not define the functions in your cpp file (if you wrote this code yourself)
2. do not include the lib/dll file that contains the definitions

If in C++, may be 

A common mistake is that you define a function as a standalone and forget the class selector, e.g. A::, in your .cpp file:

Reference:

https://stackoverflow.com/questions/9928238/unresolved-external-symbol-in-object-files

2. ARMCC: Error #268: declaration may not appear after executable state

除了要記得在header 檔先declare function, 並且在C檔中 include header 檔之外(路徑需找的到)

C90中規定變數的定義必須在可執行的函數之前

In C90, all variable declarations must happen before any executable statements in a function or other code block.

The compiler error message mentions the line number of the offending line of code.

Reference:

http://www.keil.com/support/docs/3677.htm