I'm just beginning to get into C++ and I want to pick up some good habits. If I have just allocated an array of type int
with the new
operator, how can I initialise them all to 0 without looping through them all myself? Should I just use memset
? Is there a “C++” way to do it?
It's a surprisingly little-known feature of C++ (as evidenced by the fact that no-one has given this as an answer yet), but it actually has special syntax for value-initializing an array:
new int[10]();
Note that you must use the empty parentheses — you cannot, for example, use (0)
or anything else (which is why this is only useful for value initialization).
This is explicitly permitted by ISO C++03 5.3.4[expr.new]/15, which says:
A new-expression that creates an object of type
T
initializes that object as follows:...
- If the new-initializer is of the form
()
, the item is value-initialized (8.5);
and does not restrict the types for which this is allowed, whereas the (expression-list)
form is explicitly restricted by further rules in the same section such that it does not allow array types.