c++ beginner 的菜鸟问题请问将program分在三个function的问题:
即: lab.cpp data.h data.cpp
为什么我用"inline"在data.cpp(implementation file)里的某些class member function 的前面,compile时就会出错呢?
但是去掉"inline"后就什么问题都没有了,program运行也很正常.
难道分成3个file就不能用"inline" function?
如果能用,用法还是和写在一个file里一样吗?
注:我所用到的inline function都是很小的class member function:
eg:
class Datalist {
..............
int getMonth() const;
..............
}
inline int Datelist::getMonth() const {
return month;
}
[如今 (2-21 2:13, Long long ago)]
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The use of inline, __inline, __forceinlineThe inline and __inline keywords allow the compiler to insert a copy of the function body into each place the function is called. The insertion occurs only if the compiler's cost/benefit analysis show it to be profitable. The __forceinline keyword overrides the cost/benefit analysis and relies on the judgement of the programmer instead. Exercise caution when using __forceinline. Indiscriminate use of __forceinline can result in larger code with only marginal performance gains or, in some cases, even performance losses (due to increased paging of a larger executable, for example).
You cannot force the compiler to inline a function when conditions other than cost/benefit analysis prevent it. You cannot inline a function if:
The function or its caller is compiled with /Ob0 (the default option for debug builds).
The function and the caller use different types of exception handling (C++ exception handling in one, structured exception handling in the other).
The function has a variable argument list.
The function uses inline assembly and is not compiled with /Og, /Ox, /O1, or /O2).
Function returns an unwindable object by value and is not compiled with /GX, /EHs, or /EHa).
The function receives a copy-constructed object passed by value, when compiled with /GX, /EHs,, or /EHa.
The function is recursive and is not accompanied by #pragma(inline_recursion, on). With the pragma, recursive functions can be inlined to a default depth of eight calls. To change the inlining depth, use #pragma(inline_depth, n).
If the compiler cannot inline a function declared __forceinline, it generates a level 1 warning (4714).
The inline keyword is available only in C++. The __inline and __forceinline keywords are available in both C and C++. For compatibility with previous versions, _inline is a synonym for __inline.
Using inline functions can make your program faster because they eliminate the overhead associated with function calls. Functions expanded inline are subject to code optimizations not available to normal functions.
The /Ob compiler optimization option determines whether inline function expansion actually occurs
[Yup (2-21 2:42, Long long ago)]
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i even got problem when i try to compilenormal .h file.
the code is posted.
can help me? thanks[和尚庙的主持 (2-21 9:06, Long long ago)]
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i think you also have to put inline in class defclass Datalist {
..............
inline int getMonth() const;
..............
}
but normally if I have simple function and want to make it inline.
I prefer write mathod body in class def
class Datalist {
..............
inline int getMonth() const {return month;}
..............
}
[吴永铮 (2-21 12:19, Long long ago)]
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(引用 吴永铮:i think you also have to put inline in class defclass Datalist {
..............
inline int getMonth() const;
..............
}
b...)Why need do this?The example in MSDN is just like:
class Datalist {
..............
int getMonth() const;
..............
}
inline int Datalist::getMonth() const
{
...
}
[Yup (2-21 12:24, Long long ago)]
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(引用 Yup:Why need do this?The example in MSDN is just like: class Datalist { .............. int getMonth() const; .............. } inl)let me try with GCC and others.[hash (2-21 12:26, Long long ago)] [ 传统版 | sForum ][登录后回复]6楼