I am trying to call a function named characterSelection(SDL_Surface *screen, struct SelectionneNonSelectionne sel) which returns a void
This is the .h of the function I try to call:
struct SelectionneNonSelectionne;
void characterSelection(SDL_Surface *screen, struct SelectionneNonSelectionne);
void resetSelection(SDL_Surface *screen, struct SelectionneNonSelectionne);
On my main function, I try to call it like this:
characterSelection(screen, SelectionneNonSelectionne);
When I compile, I have the message:
error: expected primary-expression before ')' token
I made the includes. I suppose I miscall the second argument, my struct. But, I can't find why on the net.
Have you got any idea about what I did wrong?
You should create a variable of the type SelectionneNonSelectionne.
struct SelectionneNonSelectionne var;
After that pass that variable to the function like
characterSelection(screen, var);
The error is caused since you are passing the type name SelectionneNonSelectionne
A function call needs to be performed with objects. You are doing the equivalent of this:
// function declaration/definition
void foo(int) {}
// function call
foo(int); // wat!??
i.e. passing a type where an object is required. This makes no sense in C or C++. You need to be doing
int i = 42;
foo(i);
or
foo(42);
You're passing a type as an argument, not an object. You need to do characterSelection(screen, test); where test is of type SelectionneNonSelectionne.
I seen this problem with the latest nightly build of Code::Blocks. When I switched back to the stable release of Code::Blocks, 20.03 at the time of this writing, the problem went away and my code compiled and ran without problems. I'm not sure what Code::Blocks is doing, but it is very annoying. I got this repeatedly on a C++ project for every NULL in my code, forcing me to use nullptr instead.
Related
I am developing an embedded system with the mbed framework in C++.
To attach an interrupt function to the serial interrupt, I normally do this:
Serial pc(pin_u_tx, pin_u_rx,115200);
void SerialStart(void) {
...
pc.attach(&SerInt);
...
}
void SerInt(){
...
}
But now I need to do the same thing from inside a class, and it doesn't work as I can't refer to an internal function:
CTCOMM::CTCOMM()
{
pc = new Serial(ser_tx, ser_rx, ser_baud);
pc->attach(&serial_interrupt);
}
void CTCOMM::serial_interrupt() {
...
}
I tried a few ways, but none works:
pc->attach(&serial_interrupt);
gives the error
lib\CTcomm\ctcomm.cpp:12:17: error: ISO C++ forbids taking the address of an unqualified or parenthesized non-static member function to form a pointer to member function. Say '&CTCOMM::serial_interrupt' [-fpermissive]
pc->attach(*serial_interrupt);
gives the error
lib\CTcomm\ctcomm.cpp:12:17: error: invalid use of member function 'void CTCOMM::serial_interrupt()' (did you forget the '
pc->attach(*serial_interrupt());
gives the error
lib\CTcomm\ctcomm.cpp:12:33: error: void value not ignored as it ought to be ()' ?)
pc->attach((*this)->*(serial_interrupt));
gives the error
lib\CTcomm\ctcomm.cpp:12:23: error: invalid use of non-static member function 'void CTCOMM::serial_interrupt()'
and so on (I tried more suggestions found here, but got no succes).
What would be the correct way to point to that function?
Try this.
pc->attach(callback(this, &CTCOMM::serial_interrupt));
pc->attach(this, &CTCOMM::serial_interrupt); should also work. But it is deprecated in the recent versions of mbed OS.
Here is the latest Mbed API:
https://os.mbed.com/docs/v5.10/mbed-os-api-doxy/classmbed_1_1_serial.html
I have this really simple line of code in my production-code(A.cpp) as follows:
std::string A::getString(int i) {
return sVect_[i];
}
with the header as follows:
class A{
public:
std::string getString(int i);
...
private:
vector<std::string> sVect_;
...
};
I've been trying to test the getString() function using googletest but an error keeps popping out:
error: invalid conversion from 'char* (*)(const char*, int)throw ()' to 'int'
error: initializing argument 1 of 'std::string A::getString(i)'
This was my test program:
TEST(ATest, getString){
A a;
EXPECT_EQ("c", a.getString(i));
}
I couldn't quite grasp the workaround of the vector string and how to call it in my test program without ever changing the production code. I even use the hack, adding #define statements, to access the private member but still couldn't do it.
How do my test actually looks like to successfully call that function?
Note: I'm on Linux and using gcc. Thank you in advance guys.
Perhaps the error message is misleading. Have you defined i globally somewhere else? To me it looks like in the local scope because it does not know what the value of the variable i is, it is misbehaving in an unexpected way
TEST(ATest, getString){
A a;
EXPECT_EQ("c", a.getString(i)); //here what is the 'i' and where is it defined
}
I'm trying to wrap a c++ function called i_receive() by following this tutorial, I first created a wrap.c file, the content of this file is like this:
int i_receive(const uint32_t *f, int32_t t){
static int (*real_i_receive)(const uint32_t *, int32_t)=NULL;
printf("hello world");
return real_i_receive;
}
I compiled this file with gcc -fPIC -shared -o wrap.so wrap.c -ldl, when I used the LD_PRELOAD to run some C++ code with LD_PRELOAD=/full/path/to/wrap.so ./mycppcode I got this message:
ERROR: ld.so: object '/full/path/to/wrap.so' from LD_PRELOAD cannot be preloaded: ignored`.
I was guessing the reason might be that the wrap file is a C file, and I'm using it with C++ code, am I right?
I changed the file to wrap.cc with the same content, when compiling in the same way as before, I got:
ERROR: invalid conversion from 'int (*)(const uint32_t*, int32_t)' to 'int'
First of all, your 2nd error your are getting becase you are returning a Pointer to function type instead of a int type.
If you want to return an int, call the function from the code :
return real_i_receive(f,t);
Notice the "()" which means a function call.
Regarding your guess : it doesn't matter if you are using C or C++ code, the libaries are all assembly code.
One difference between exporting C functions and C++ functions is the name mangling. You would rather export a function as a C function to be able to access it inside your library through unmagled name.
To export a function without name mangling it, you can use extern "C" .
Replace
return real_i_receive;
with
return real_i_receive(f, t);
As it is, the return type of your function is int but you're returning a function pointer.
I have the following decleration in file Order.h (Holdng class Order) :
void removeFromAlbum(int barcode);
and the following Implementation line:
void Order::removeFromAlbum(int barcode)
But, when im trying to call the function with a different file, Store.cpp (Order.h was included) with the following line :
order.removeFromAlbum(barcode);
I get the following error from eclipse :
Invalid arguments '
Candidates are:
void removeFromAlbum(int)
'
Eclipse is well defined.
Any suggestions ?
Edit :
This is the function when all the magic happens :
void Store::removeFromOrder(int ordNum, int barcode)
barcode is an int.
EDIT: Before the OP's edit, it was impossible to tell if barcode was an integer. This answer may, therefore, be invalid:
It looks like you're trying to call the function removeFromAlbum() with a type that isn't an int. Ensure that barcode is actually cast as an int.
I have a problem compiling a c++ program with gcc version 4.6.3; I can compile this program with microsoft compiler (v 9.0) without problems.
This program is using some of my libraries I always used with microsoft compiler.
problem is when I try to pass a reference as argument that is a subtype of another: pseudo example here:
class ObjManager{..}
class SubObjMng : public ObjManager{
public:
inline SubObjMng() : ObjManager(0, ... ){}
};
class Test{
public:
Test(int i, ObjManager &obj_mng);
}
int main(){
SubObjMng myobjmng;
Test t(0, myobjmng); //GCC ERROR HERE
}
output of the error is (real output for my program):
globals.h:227:40: error: no matching function for call to cdk::HashMap::HashMap(unsigned int, cdk::PtrObjMng, cdk::cstrObjMng)
globals.h:227:40: note: candidates are:
contrib/cdklib/cdk_struct.h:485:12: note: cdk::HashMap::HashMap(uint32_t, cdk::ObjManager&, cdk::ObjManager&)
contrib/cdklib/cdk_struct.h:485:12: note: no known conversion for argument 2 from cdk::PtrObjMng to cdk::ObjManager&
anyone can help?
thanks!
cdk::PtrObjMng should inherit from cdk::ObjMng, making polymorphism possible through references. Otherwise this is a no-go according to what the compiler says.
Of course this might not be the root of your problem, I wish we could see the implementation of your constructor.