uint8_t and unsigned char linking error

Question

I'm using template function:

template<typename T> void func(const T& value)
{
    obj->func(value);
}

where obj is object of class:

void my_object::func(int64_t value) { ... }
void my_object::func(uint64_t value) { ... }
void my_object::func(uint32_t value) { ... }
void my_object::func(uint16_t value) { ... }
void my_object::func(uint8_t value) { ... }

The problem is with uint8_t overload of my_object::func() override. Linker complains about unresolved external symbols to overloads, which should have unsigned char parameter.

Should I replace uint8_t overload with unsigned char overload?

Edit: Just now noticed, that linker complains about uint64_t and int64_t too.

I compile on Windows using MSVC++ 2008 Express.

Edit: Apologies, I declared my_object::func(uint8_t value) function (and other), but I didn't defined it.

Breakthrough

Incidentally, what is your compiler? – Fulgurous

What is the exact error message you're getting? – Stentor

You should try to reduce the problem scope and give more details on what you are actually doing. Is it really because of the template - what happens if you make a direct call of obj::func() instead? How do you define your class, and where and how you have it implemented? With only the description that you provided people would have to guess what is actually happening. – Aholla

Make sure you use the same headers and thus typedefs of those integer types. MSVC has defects with how it resolves equivalent types. In certain cases two types are C++ identical but MSVC has distinct internal types for them. Those internal types make it to the linker, thus a mismatch. – Antilebanon

Answer 1

This is the include file should #include to use the above mentioned types (C99 recommendations)

#include <stdint.h>

Drear

It leads to link errors because the include you have to #include will not have converted before compilation via the typedef declarations all the int32... In other terms, during compilation all the above mentioned special types do not exist anymore - thus they are not present during linking either. – Fulgurous

stdint.h was included into C99 in order to help programs portability. It is also available on Windows. See en.wikipedia.org/wiki/Stdint.h – Fulgurous

Should really be #include <cstdint> for C++ programs. That header isn't included with VS2008, but you can find a compatible file in several places on the 'net. – Malvina

Answer 2

I'm guessing that uint8_t has been typedefed as unsigned char, hence why you're seeing that.

Prieto

Looking at the source, no. uint8_t is typedef for UINT8. – Breakthrough

hm.. I am not sure but uint8_t belongs to stdint.h which purpose is to abstract away from primitive types which might in turn be different in different platforms. – Cuddle

The library I'm working with has include file, which differentiate between build environments. If it's windows it defines all int types manually, if Linux it includes stdint.h and inttypes.h – Breakthrough

Answer 3

Try compiling with

template void my_object::func(int64_t value) { ... }
template void my_object::func(uint64_t value) { ... }
template void my_object::func(uint32_t value) { ... }
template void my_object::func(uint16_t value) { ... }
template void my_object::func(uint8_t value) { ... }

fixed my problem with a similar issues

Anuradhapura