Are delphi variables initialized with a value by default?

Class fields are default zero. This is documented so you can rely on it. Local stack varaiables are undefined unless string or interface, these are set to zero.

Just as a side note (as you are new to Delphi): Global variables can be initialized directly when declaring them:

var myGlobal:integer=99;

Global variables that don't have an explicit initializer are allocated in the BSS section in the executable. They don't actually take up any space in the EXE; the BSS section is a special section that the OS allocates and clears to zero. On other operating systems, there are similar mechanisms.

You can depend on global variables being zero-initialized.

Yes, this is the documented behaviour:

• Object fields are always initialized to 0, 0.0, '', False, nil or whatever applies.

• Global variables are always initialized to 0 etc as well;

• Local reference-counted* variables are always initialized to nil or '';

• Local non reference-counted* variables are uninitialized so you have to assign a value before you can use them.

I remember that Barry Kelly somewhere wrote a definition for "reference-counted", but cannot find it any more, so this should do in the meantime:

reference-counted == that are reference-counted themselves, or directly or indirectly contain fields (for records) or elements (for arrays) that are reference-counted like: string, variant, interface or dynamic array or static array containing such types.

Notes:

• record itself is not enough to become reference-counted
• I have not tried this with generics yet