reinterpret or static_cast?

[Frank A. Uepping]

Hi,
look at this function, which does some low-level IO.

void writen(int fd, const void* data, size_t size)
{
while (size) {
int n = write(fd, data, size);
if (n < 0)
throw logic_error...

static_cast<const char*>(data) += n; // reinterpret_cast?
size -= n;
}
}

Here it is necessary to do a cast in order to do some pointer arithmetic.
Is the static_cast or the reinterpret_cast appropriate?

/FAU

 

[Ron Natalie]

Here it is necessary to do a cast in order to do some pointer arithmetic.
Is the static_cast or the reinterpret_cast appropriate?

I'd prefer static_cast (in it's undo defined conversions role), but I don't know that
it is more appropriate than reinterpret_cast in this case.

 

[Andrey Tarasevich]

Hi,
look at this function, which does some low-level IO.

void writen(int fd, const void* data, size_t size)
{
while (size) {
int n = write(fd, data, size);
if (n < 0)
throw logic_error...

static_cast<const char*>(data) += n; // reinterpret_cast?

This will not even compile. The result of this cast in an rvalue.
Operator '+=' cannot be applied to an rvalue. Most likely is was
supposed to be

static_cast<const char*&>(data) += n

But I don't think this is a valid technique, regardless of the cast
operator used. The more proper way to do this would be the following