Value initialization

[dman]

Something thats very new to me is the initialization of vars etc that are not 0 or null. I assume this is because c++ just allocates a memory slot without resetting its content.

My question is this, if i have a class or struct that has several vars in it, is there a quick way of zeroing all the values without having to do them all in the CTOR?

[Bazzy]

The constructor is there for that, if you don't like having several assignments or a long initializer lists you can do something like this:
var1 = var2 = var3 = 0;
so you assign 0 to every variable in a single line but you have to assign a value somewhere and initializer lists are the best places to do that

[dman]

hmm, better than nothing i guess :)
thanks for the info.

Dont suppose you know if theres an automatic build constructor tool in codeblocks by chance (i have about 100 vars to reset :( )

[seymore15074]

There is array-style initialization of structs, but I don't recommend it...

For example:

struct Obj
{
    int a, b;
}
//...
Obj obj = {};

That should zero out obj.a and obj.b, but that syntax is not allowed for classes. Also, I have no idea what will happen if the members are not all numbers...

The constructor initialization list is the best way to go.

[jsmith]

If you want default construction of POD types to initialize the variables, you can use boost::value_initialized<> template.

boost::value_initialized<int> x;  // x == 0 now 

[seymore15074]

I love it when you post boost stuff, jsmith. We don't use it where I work and I've been meaning to familiarize myself with it on my own...of course, I haven't gotten around to it... Right now I'm busy reading up on Qt.

My point is, keep it up; maybe someday I'll start remembering these things!