C++ windows code links in 64bit but not in 32bit

I have code written in C++ on windows. My code compiles and links when I compile it as x64 but not when I change the build configuration to x86.

The failure is a linking error.

I'm using the function RtlIsNameInExpression from ntdll.

When I compile it in 32bit mode I get a linkage error (LNK2019) of unresolved external.

Any ideas why this might happen?

10x

Solution

first of all - how you declare function and which symbol can not found linker ?

declaration must be

extern "C" NTSYSAPI BOOLEAN NTAPI RtlIsNameInExpression(
                               _In_     PCUNICODE_STRING Expression,
                               _In_     PCUNICODE_STRING Name,
                               _In_     BOOLEAN         IgnoreCase,
                               _In_opt_ PWCH            UpcaseTable
                               );

i can guess that you miss NTAPI i.e __stdacall keyword if you copy-paste from here. for x64 exist only one calling convention, but for x86 exist different between __stdcall and __cdecl for example. this can explain why this found in x64 but not found in x86

what error give you linker (not compiler !) ? unresolved external symbol __imp__RtlIsNameInExpression ? (if yes you really forget __stdcall set) or __imp__RtlIsNameInExpression@16 ? in this case you declare function correct, but your ntdll.lib not containing this symbol. (may be you use old ntdll.lib for xp ? ) simply search __imp__RtlIsNameInExpression@16 string as is in ntdll[p].lib - are it found ? if not you have old (xp) version of ntdll i guess.