C++ What is the use of a implict default constructor provided by the comiler ?

[carbon]

In C++ if no user defined constructor is provided for a class the compiler automatically provides a implicit default constructor.

An implicit default constructor is equivalent to a default constructor with no parameters and no body ?

So what is the use of a implicit default constructor provided by the compiler, if it is not going to do anything ?

[weaknessforcats]

The default constructor calls the constructor for each member of your class. So it does something. Like here:

MyClass obj;

obj will have each member initialized by calling its constructor.

[coderHead]

You say each member is initialized by calling its constructor. OK, initialized to what? To whatever the constructor feels like? LOL. I mean if no user defined constructor is provided then where are the initializing values coming from?

[weaknessforcats]

The compiler knows how to initialize the built-in types but if your class has user-defined type as a member and there is no default constructor for that type, then your compile fails on this code:

MyClass obj;
 

Initialization is a big deal in C++ since major initialization errors in C slip by the C compiler. One of the C++ goals was to plug these errors at compile time rather than when the program was running.

C does not do member-wise initialization. It doesn't do any initialization at all. There is reliance on the mem--- functions which can easily screw up the stack.