C里面的#pragmaweak的含义 c pragma

#pragma weak function_name

defines function_name to be a weaksymbol. The linker does not complain if it does not find adefinition for function_name.

#pragma weak function_name1 = function_name2

defines function_name1 to be a weaksymbol, which is an alias for the symbolfunction_name2. You must declarefunction_name1 and function_name2before using them in the pragma. For example:

extern void bar(int) extern void _bar(int) #pragma weak _bar=bar

If your program calls but does not definefunction_name1, the linker uses the definition fromthe library. However, if your program defines its own version offunction_name1, then the program definition is usedand the weakglobal definition of function_name1 in the library isnot used. If the program directly callsfunction_name2, the definition from the library isused; a duplicate definition of function_name2 causesan error.

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