克++未定義的引用，雖然所有的文件包括

Question

我有問題，作爲++嘗試我收到以下錯誤的對象文件鏈接的G：這是爲什麼，因爲例如情況

11:29:13 **** Build of configuration Debug for project daytime **** 
make all 
'Building target: daytime' 
'Invoking: Cross G++ Linker' 
g++ -o "daytime" ./tcf/services/daytime.o ./tcf/main/main.o 
./tcf/services/daytime.o: In function `command_get_time_of_day': 
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:38: undefined reference to `json_read_string' 
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:40: undefined reference to `exception' 
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:43: undefined reference to `exception' 
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:52: undefined reference to `write_stringz' 
makefile:46: recipe for target 'daytime' failed 
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:54: undefined reference to `write_stringz' 
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:56: undefined reference to `write_errno' 
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:58: undefined reference to `json_write_string' 
./tcf/services/daytime.o: In function `ini_daytime_service': 
C:\Users\falkstef\runtime-EclipseApplication\daytime\Debug/../tcf/services/daytime.c:70: undefined reference to `add_command_handler' 
collect2.exe: error: ld returned 1 exit status 
make: *** [daytime] Error 1 

我不知道包括並找到#include <tcf/framework/json.h>。

沒有的gcc編譯相應的*.c文件，出現這個連接錯誤？ 這裏有什麼問題？

謝謝。

Answer 1

僅包含頭文件是不夠的;您還必須指定定義這些函數的庫。

要使鏈接器找到所有這些方法/類（json_read_string,write_stringz, exception），您需要引用該庫。如果例如它們包含在一個名爲libjson.so庫，你應該做的：

g++ -ljson -o "daytime" ./tcf/services/daytime.o ./tcf/main/main.o 

（或庫添加到項目選項，如果Eclipse管理您的make文件）。

或者，如果它的另一個.o文件將包括在彙編（ - >或項目，如果Eclipse創建make文件）。