How to malloc an array in heap like C?

[Dushistov]

@eadren

The primary purpose is test the performance of vector production which is implemented either in C(int *) or C++(vector) comparing with Rust

IMHO there is no sense in this comparison. Rust have no "runtime" I mean GC or interpreter.
Rust compiler share backend with clang. So if you dare to use unsafe and satisfied with code that generates clang for C/C++ you always can write Rust code that will produce the same assembly as any C++ code (clang).

[381]

I tried this one is 27s faster than C++ version. (tried both clang and g++ ends ~80s, but the following version takes only 57s)

    for a in  v1.iter().take(1000) {
        for (b,t) in v2.iter().zip(vsum.iter_mut()) {
            *t += a * b;
        }
    }

And I believe this one can avoid bounds check.

[vks]

@kornel

let has_known_length = &vec[0..len];
for i in 0..len {
    has_known_length[i]; // probably not bounds checked anymore, if llvm can see both 0..len
}

You can alternatively but an assert_eq!(vec.len(), len); in front of the loop.