Can a member struct be zero-init from the constructor initializer list without calling memset?
- by selbie
Let's say I have the following structure declaration (simple struct with no constructor).
struct Foo
{
int x;
int y;
int z;
char szData[DATA_SIZE];
};
Now let's say this struct is a member of a C++ class as follows:
class CFoobar
{
Foo _foo;
public:
CFoobar();
};
If I declare CFoobar's constructor as follows:
CFoobar::CFoobar()
{
printf("_foo = {%d, %d, %d}\n", _foo.x, _foo.y,_foo.z);
for (int x = 0; x < 100; x++)
printf("%d\n", _foo.szData[x]);
}
As you would expect, when CFoobar's constructor runs, garbage data gets printed out Obviously, the easy fix is to memset or ZeroMemory &_foo. It's what I've always done...
However, I did notice that if add _foo to the constructor's initialization list with no parameters as follows:
CFoobar::CFoobar()
: _foo()
{
That this appears to zero-out the member variables of _foo. At least that was the case with g++ on linux.
Now here's my question: Is this standard C++, or is this compiler specific behavior?
If it's standard behavior, can someone quote me a reference from an official source? Any "gotchas" in regards to implicit zero-init behavior with more complicated structs and classes?
