what can i do with c?

Hi all.
First, let talk about the differences between C and C++. C is a programming structured language designed in 1970, C++ is an its evolution, that adds some concepts about object oriented programming. The relatinships between the two language is very strict, so C is considered an subset of C++.
If you use C you'll develop with the (old) programming structured principles, while if you use C++ you'll develop with the (new) Object Oriented principles. Yes, C is very powerful but the problem is when using it: in my opinion C is more efficient than C++, but C++ is more "advanced" than C, so one should use C when performances are critical (for example real time application).

It depends what you want to do. If you are going to be coding something that is going to be processor intensive, then you will most likely want to program it in C/C++ because you will get the fastest runtime performance. But if you want to say program a nice GUI app and you are not going to be hitting the processor heavily in the underlying functionality, then you might want to try using a higher level scripting language. The reason for this is to get the same functionality that you would get from a handful of lines from a scripting language(e.g. tk/Python), you would end up writing thousands of lines in standard C++. Visual C++ helps bridge this gap, but it is not very portable. It's important to choose the correct language for the task.

It is a myth however that C produces either faster code or smaller binaries.

The speed part I will agree with you, it is a myth. It is NOT a myth that it produces smaller binaries. The lack of mangled names in *.obj files that the linker links together to become an executable, ensures a smaller output file. Import and Export tables. That and runtime checks in C++.

It's not a myth that C equivalent code is smaller than the C++ equivalent. I know, I have implemented 'classes' in C with manual VTable creation, it ends up a smaller *.dll for sure.

typedef struct _MYCLASS_VTABLE
{
void * Reserved; // TypeData reserved member
void (__stdcall * Destructor)(void * lpObject);
void (__stdcall * SetValue)(void * lpObject,int Value);
int (__stdcall * GetValue)(void * lpObject);
} MYCLASS_VTABLE;

typedef struct _MYCLASS
{
const MYCLASS_VTABLE * pvTable;
// Data Members
int Value;
} MYCLASS;

#define VirtualCall(obj,Function) (obj->pvTable->*Function)

void __stdcall MyClassDestructor(MYCLASS * pObject)
{
}

void __stdcall MyClassSetValue(MYCLASS * pObject,int value)
{
pObject->Value = value;
}

int __stdcall MyClassGetValue(MYCLASS * pObject)
{
return pObject->Value;
}

static const MYCLASS_VTABLE_DATA = { 0, MyClassDestructor, MyClassSetValue, MyClassGetValue };

MYCLASS * CreateObject()
{
MYCLASS * pClass = (MYCLASS *)malloc(sizeof(MYCLASS));

pClass->pvTable = &MYCLASS_VTABLE_DATA; // assign the vtable data
pClass->Value = 100; // give it a default value

return pClass;
}

void DestroyObject(MYCLASS * pObject)
{
VirtualCall(pObject,Destructor)(pObject);

free(pObject);
}