Variation between C# and Java when converting long to byte array

Question

I'm not experienced in Java and so this is going straight over my head:-

Java Code:

long foo = 1234567890;
byte[] boo = ByteBuffer.allocate(8).putLong(foo).array();

C# Code:

long foo = 1234567890;
byte[] bar = BitConverter.GetBytes(foo);

// reverse to match Java's Big Endianess
byte[] boo = bar.Reverse().ToArray();

In the Java sample, boo = 0, 0, 0, 0, 73, -106, 2, -46

However in C#, boo = 0, 0, 0, 0, 73, 150, 2, 210

Can someone with a bigger brain, explain why these differ?

Many thanks!

David Yaw · Accepted Answer · 2011-03-29 18:09:25Z

12

Java is using signed bytes, C# is using unsigned. Note that all values < 127 match, and values > 128 are converted to a negative number. If you converted the C# array from byte to sbyte, the values would match.

answered Mar 29, 2011 at 18:09

David Yaw

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3 Comments

Heinzi Over a year ago

Exactly. The corresponding data type in C# is sbyte (signed byte).

Elian Ebbing Over a year ago

More specific: for values > 127 the Java value is the C# value subtracted by 256.

Vivin Paliath Over a year ago

Shouldn't have deleted my answer :) This is what I wrote. Have an upboat!

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