[英]g++ throws “undefined reference to” static class member
I'm writing CCITT Group 4 encoder and it seems I have a problem with linker. 我正在编写CCITT Group 4编码器,看起来我的链接器有问题。
I have some raw binary data stored as static const
class members ( Fakskod.h
): 我有一些原始二进制数据存储为static const
类成员( Fakskod.h
):
class Fakskod {
public:
// ...
static const unsigned char codesTerminateWhite[64][3];
static const unsigned char codesTerminateBlack[64][3];
static const unsigned char codesMakeUpWhite[40][3];
static const unsigned char codesMakeUpBlack[40][3];
private:
//...
} ;
I had to initialize them elsewhere, because brace-enclosed initializers can't be used in class definition. 我不得不在其他地方初始化它们,因为括号封闭的初始化器不能在类定义中使用。 Not to mention clearness of the header. 更不用说标题的清晰度了。 So in another file ( Fakskod-codes.cpp
) I assigned data: 所以在另一个文件( Fakskod-codes.cpp
)中我分配了数据:
const unsigned char codesTerminateBlack[64][3] = { {0x0d, 0xc0, 0xa},
{0x40, 0x0, 0x3}, {0xc0, 0, 0x2}, {0x60, 0, 0x3}, {0x30, 0, 0x4},
{0x20, 0, 0x4}, {0x18, 0, 0x5}, {0x14, 0, 0x6}, {0x10, 0, 0x6},
//... (~200 hex bytes)
} ;
And that's what I got: 这就是我得到的:
/tmp/ccm0ijoi.o: In function `Fakskod::makeCode(int, fkColor)':
rectangle_test.cpp:(.text+0x19b0): undefined reference to `Fakskod::codesTerminateWhite'
rectangle_test.cpp:(.text+0x1a02): undefined reference to `Fakskod::codesMakeUpWhite'
rectangle_test.cpp:(.text+0x1a7b): undefined reference to `Fakskod::codesTerminateWhite'
rectangle_test.cpp:(.text+0x1b0f): undefined reference to `Fakskod::codesTerminateBlack'
rectangle_test.cpp:(.text+0x1b5e): undefined reference to `Fakskod::codesMakeUpBlack'
rectangle_test.cpp:(.text+0x1bce): undefined reference to `Fakskod::codesTerminateBlack'
collect2: error: ld returned 1 exit status
It seems the source of trouble is this method ( Fakskod-Horizontal.cpp
): 似乎麻烦的来源是这种方法( Fakskod-Horizontal.cpp
):
std::vector<unsigned char> Fakskod::makeCode(int num, fkColor color) {
#define FAKSKOD_MKCD(TERM, MKUP) \
if(num < 64) \
return vectorize( TERM [num]); \
else { \
for(int i=40; i>0; i--) \
if(num/64 == i) { \
code = vectorize( MKUP [i-1]); \
num -= 64 * i; \
} \
return mergeStreams(code, vectorize( TERM [num])); \
}
std::vector<unsigned char> code;
if(color==WHITE) { FAKSKOD_MKCD(codesTerminateWhite, codesMakeUpWhite) }
else { FAKSKOD_MKCD(codesTerminateBlack, codesMakeUpBlack) }
} // Fakskod::makeCode
I'm sure that everything is ok with the macro. 我确信宏的一切都还可以。 Preprocessor ( g++ -E
) resolves it correctly and when I paste expanded version to my code, the message is the same. 预处理器( g++ -E
)正确解析它,当我将扩展版本粘贴到我的代码时,消息是相同的。
Also I tried to #include
the header file and Fakskod-codes.cpp
, or add these files to g++ command. 我还尝试#include
头文件和Fakskod-codes.cpp
,或者将这些文件添加到g ++命令。 Didn't help. 没有帮助。 Error raises even if I move assignments to header. 即使我将分配移动到标头,错误也会增加。
The static
class members you have declared are really named Fakskod::codesTerminateWhite
and so on. 您声明的static
类成员实际上名为Fakskod::codesTerminateWhite
,依此类推。 When you define them in the source file, you're no longer within the class scope, so you need to type the full name: 在源文件中定义它们时,您不再在类范围内,因此您需要键入全名:
const unsigned char Fakskod::codesTerminateBlack[64][3] = {
// ...
};
Without that, C++ thinks they are two different arrays. 没有它,C ++认为它们是两个不同的数组。
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