Suppose I have a class
class C { C(int a=10); }; why if I call
C c; the contructor C(int =10) is called and if I call
C c(); the default constructor is called? How to avoid this? I want to execute only my constructor, I tried to make the default constructor private, but it doesn't work.
C c(); should be parsed as a function declaration. In order to explicitly invoke the default-constructor, you need to write C c = C();.explicit, to prevent implicit conversions from kicking in at unexpected moments. The code C c(); doesn’t do what you think it does:
It declares a function called c that takes no arguments and returns a C. It is equivalent to
C c(void); 
This is because the c() is interpreted as a function named c. C() will trigger the appropriate constructor for the C class
warning C4930: 'C c(void)': prototyped function not called (was a variable definition intended?)I know other compilers will as well, but the ones I have readily available at the moment don't.