Hi Phil,
Looking at some cctbx C++ code, I note use of syntax like
int i = 1234; double d = static_cast<double>(i);
How is this different or indeed preferable to
double d = double(i);
or
d = i;
?
Short answer: For conversions between non-pointer types, it does not matter but for pointer types, static_cast shall always be used to the exclusion of any other conversion.
The language lawyer:
The construct
double d = double(i)
which is known as functional-style cast is completely equivalent to the so-call cast notation, which comes from C:
double d = (double)i
You may see both in a few places in the cctbx code actually.
The problem with those two constructs is that the compiler will let use convert a pointer to anything into a pointer to anything else. Consider:
#include <iostream>
struct foo {
int i,j;
foo(int i, int j): i(i), j(j) {}
};
struct bar {
double d;
bar(double d): d(d) {}
};
int main() {
foo x(1, 2);
bar *y = (bar *)&x;
std::cout << y->d << std::endl;
return 0;
}
This prints 4.24399e-314 on my computer but this depends on the compiler. On the contrary,
bar *y = static_cast