unresolved external symbol __imp__fprintf and __imp____iob_func, SDL2

To Milan Babuškov, IMO, this is exactly what the replacement function should look like :-)

FILE _iob[] = {*stdin, *stdout, *stderr};

extern "C" FILE * __cdecl __iob_func(void)
{
    return _iob;
}

I have finally figured out why this is happening !

In visual studio 2015, stdin, stderr, stdout are defined as follow :

#define stdin  (__acrt_iob_func(0))
#define stdout (__acrt_iob_func(1))
#define stderr (__acrt_iob_func(2))

But previously, they were defined as:

#define stdin  (&__iob_func()[0])
#define stdout (&__iob_func()[1])
#define stderr (&__iob_func()[2])

So now __iob_func is not defined anymore which leads to a link error when using a .lib file compiled with previous versions of visual studio.

To solve the issue, you can try defining __iob_func() yourself which should return an array containing {*stdin,*stdout,*stderr}.

Regarding the other link errors about stdio functions (in my case it was sprintf()), you can add legacy_stdio_definitions.lib to your linker options.

Microsoft has a special note on this (https://msdn.microsoft.com/en-us/library/bb531344.aspx#BK_CRT):

The printf and scanf family of functions are now defined inline.

The definitions of all of the printf and scanf functions have been moved inline into stdio.h, conio.h, and other CRT headers. This is a breaking change that leads to a linker error (LNK2019, unresolved external symbol) for any programs that declared these functions locally without including the appropriate CRT headers. If possible, you should update the code to include the CRT headers (that is, add #include ) and the inline functions, but if you do not want to modify your code to include these header files, an alternative solution is to add an additional library to your linker input, legacy_stdio_definitions.lib.

To add this library to your linker input in the IDE, open the context menu for the project node, choose Properties, then in the Project Properties dialog box, choose Linker, and edit the Linker Input to add legacy_stdio_definitions.lib to the semi-colon-separated list.

If your project links with static libraries that were compiled with a release of Visual C++ earlier than 2015, the linker might report an unresolved external symbol. These errors might reference internal stdio definitions for _iob, _iob_func, or related imports for certain stdio functions in the form of __imp_*. Microsoft recommends that you recompile all static libraries with the latest version of the Visual C++ compiler and libraries when you upgrade a project. If the library is a third-party library for which source is not available, you should either request an updated binary from the third party or encapsulate your usage of that library into a separate DLL that you compile with the older version of the Visual C++ compiler and libraries.