DLL function(s) problem

[silur]

Simple question i have this code in an EXE:

void foo(int var1);
void foo(int var1,int var2);

void foo(int var1);
void foo(int var1,int var2);

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so i can use both with the same name
how can i use this in a DLL my Qt compiler says that the 2 function confilts

[amleto]

there are plenty of other resources on the net available for building (c++) dlls. This is nothing to do with Qt programming.

[silur]

Qt is C++ , i didn't ask for trolling i asked for advice...

[amleto]

Qt is not c++. Qt is a library built with c++.

This is a Qt programming forum. You have not asked a Qt programming question.

Maybe here http://www.qtcentre.org/forums/9-General-Programming is what you are looking for.

[silur]

look go flame somewhere else i have a question i don't need a lecture what Qt u know I'M PROGRAMMING IN Qt do you think i don't know what it is?
you are a programmer in Qt, so rather than trollin' answer or flame another post

[spirit]

Well, you've posted in a wrong forum. That's it. If you're sure that's the correct place to ask then:
Did you fill HEADERS & LIBS variables for your pro-file? What's the complete error message?

[amleto]

look go flame somewhere else i have a question i don't need a lecture what Qt u know I'M PROGRAMMING IN Qt do you think i don't know what it is?
you are a programmer in Qt, so rather than trollin' answer or flame another post

Since you asked so nicely, and the fact that you seem unable to find your way into the correct forum, I will advise you to read my signature.

[ChrisW67]

Simple question i have this code in an EXE:

void foo(int var1);
void foo(int var1,int var2);

void foo(int var1);
void foo(int var1,int var2);

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so i can use both with the same name
how can i use this in a DLL my Qt compiler says that the 2 function confilts

Firstly, there is no such beast as a Qt compiler. Your are using either a C++ or C compiler and this question has nothing to do with Qt.

Now, to address the C++ question. By way of example, this code:

#include <stdio.h>
 
void foo(int a) { printf("A = %d\n", a); }
 
void foo(int a, int b) { printf("A = %d  B = %d\n", a, b); }
 
int main(int argc, char **argv) {
    foo(1);
    foo(2,3);
    return 0;
}

#include <stdio.h>

void foo(int a) { printf("A = %d\n", a); }

void foo(int a, int b) { printf("A = %d  B = %d\n", a, b); }

int main(int argc, char **argv) {
    foo(1);
    foo(2,3);
    return 0;
}

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Is perfectly valid C++, which allows overloaded functions, and compiles just fine with a C++ compiler. Despite deliberately using only C IO functions this code will not compile with a C compiler (GCC in my case), generating:

gcc -o test main.c
main.c:7:6: error: conflicting types for ‘foo’
main.c:3:6: note: previous definition of ‘foo’ was here
main.c: In function ‘main’:
main.c:15:5: error: too few arguments to function ‘foo’
main.c:7:6: note: declared here

gcc -o test main.c
main.c:7:6: error: conflicting types for ‘foo’
main.c:3:6: note: previous definition of ‘foo’ was here
main.c: In function ‘main’:
main.c:15:5: error: too few arguments to function ‘foo’
main.c:7:6: note: declared here

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You are most likely using C++ compiler, but this is still related.


Even with a C++ compiler, if you have forward declarations in the include file for your library like this:

#ifdef __cplusplus
extern "C" {
#endif
 
void foo(int var1);
void foo(int var1,int var2);
 
#ifdef __cplusplus
}
#endif

#ifdef __cplusplus
extern "C" {
#endif

void foo(int var1);
void foo(int var1,int var2);

#ifdef __cplusplus
}
#endif

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then you are telling the C++ compiler these are C-style declarations and it will not allow the overloaded names (just like a C compiler):

g++ -o test test.cpp main.cpp 
In file included from main.cpp:1:0:
test.h:6:27: error: declaration of C function ‘void foo(int, int)’ conflicts with
test.h:5:6: error: previous declaration ‘void foo(int)’ here
main.cpp: In function ‘int main(int, char**)’:
main.cpp:6:10: error: too few arguments to function ‘void foo(int, int)’
test.h:6:6: note: declared here

g++ -o test test.cpp main.cpp 
In file included from main.cpp:1:0:
test.h:6:27: error: declaration of C function ‘void foo(int, int)’ conflicts with
test.h:5:6: error: previous declaration ‘void foo(int)’ here
main.cpp: In function ‘int main(int, char**)’:
main.cpp:6:10: error: too few arguments to function ‘void foo(int, int)’
test.h:6:6: note: declared here

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Exactly what you are doing we cannot tell, but this information should give you a clue.