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converting between bytes and ints

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RichieMac

RichieMac

Programmer
Aug 18, 2004
61
GB
Hello all,

could someone tell me if it's possible to convert bytes read from a filestream into int values to carry out some processing, then to convert back into bytes to read back to a file. What I have at the moment is a .txt file that I'm reading using FileInputStream. The data, which is read into a byte array, needs to be processed using an encoding algorithm i have built. My obvious problem is that data is read in in bytes but my algorithm requires integer values for processing. Rather than change the whole encoding prog I was hoping it wouldn't be too difficult to convert the bytes into ints - and vice versa. Is this an easy task or will I have to change the encoding/decoding prog.
 
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You could do something a bit like :

Code: 
byte[] buf ... // your byte array read from the file
DataInputStream dis = new DataInputStream(new ByteArrayInputStream(buf));
// read a single int from the stream
int i = dis.readInt();

This way, you leave your original byte data intact, but have an in-memory stream to read ints from.

Or you could just cast the bytes to ints as your iterate through the byte array.



--------------------------------------------------
Free Database Connection Pooling Software
 
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Thanks sedj. Can you just clear up for me whether i will lose data when converting back to bytes from ints. My understanding is that ints are four bytes so what will happen to remaining three bytes if I convert from int.
 
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I would not convert from ints to bytes, because you will lose precision/data.

If you use a DataOutputStream, you can use the writeInt() method.

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Free Database Connection Pooling Software
 
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Code: 
42
0
999
Save as Text.
a) It's easy to parse and read.
b) It's readable with every editor.
c) It doesn't depend on the number of bytes a language uses to store ints.
d) It can be searched from the commandline:
Code: 
grep 42 data.file

seeking a job as java-programmer in Berlin:
 
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Ah. See what you mean now. Will try that way - it may solve my problem.
 
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