CODEWITHSUNDEEP
c#
mizi_sk
mizi_sk

Reputation: 1007

How to decode one Int64 back to two Int32?

Previous question was to encode two Int32 into one Int64 [C# - Making one Int64 from two Int32s

Question: How to decode one Int64 back to two Int32 ?

Upvotes: 3

Views: 3854

Answers (2)

Mark H
Mark H

Reputation: 13907

Here's a (cheap) solution that will work for both conversions.

[StructLayout(LayoutKind.Explicit)]
public struct UnionInt64Int32 {
    public UnionInt64Int32(Int64 value) {
        Value32H = 0; Value32L = 0;
        Value64 = value;
    }
    public UnionInt64Int32(Int32 value1, Int32 value2) {
        Value64 = 0;
        Value32H = value1; Value32L = value2;
    }
    [FieldOffset(0)] public Int64 Value64;
    [FieldOffset(0)] public Int32 Value32H;
    [FieldOffset(4)] public Int32 Value32L;
}

An obvious drawback to this though, it's unportable. The Value32H and value32L will be reversed on different endian platforms.

Upvotes: 3

Jon Skeet
Jon Skeet

Reputation: 1502476

Something like this:

long x = ...;

int a = (int) (x & 0xffffffffL);
int b = (int) (x >> 32);

It's just possible that the masking in the first form is unnecessary... I can never remember the details around narrowing conversions and signed values, which is why I've included it :)

Upvotes: 8

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