Solved

java reading an unsigned int from file (into an int) and showing me the value as negative

Posted on 2014-09-03
8
393 Views
Last Modified: 2014-09-11
Hi Experts,

I'm reading an int from a stream in java and I know what I'm reading is an unsigned int, and obviously it's a big number because I get the negative sign on it (representation is negative because the negative bit is set).

I would like to know what the int value of -1083351007 is as an unsigned int?

Thanks,
Mike
0
Comment
Question by:thready
  • 2
  • 2
  • 2
  • +2
8 Comments
 
LVL 28

Assisted Solution

by:pepr
pepr earned 200 total points
ID: 40302114
I am not good in Java, but as far as I know, there is no unsigned integer there. You need to declare the variable as long (or the class Long wrapper).
0
 
LVL 37

Accepted Solution

by:
Neil Russell earned 100 total points
ID: 40302120
0
 
LVL 28

Assisted Solution

by:pepr
pepr earned 200 total points
ID: 40302130
If you know you need to get only four bytes from the stream, you may need to read it as four bytes, detect the endianness, and compose the long value out of those four bytes.
0
Courses: Start Training Online With Pros, Today

Brush up on the basics or master the advanced techniques required to earn essential industry certifications, with Courses. Enroll in a course and start learning today. Training topics range from Android App Dev to the Xen Virtualization Platform.

 
LVL 5

Assisted Solution

by:Jan Louwerens
Jan Louwerens earned 100 total points
ID: 40302136
It look like it's overflowing as an int value. Try readind it as a long value.

To convert that number into it's unsigned equivalent:
      int intValue = -1083351007;
      long longValue = Long.valueOf(intValue & 0xFFFFFFFFl);

Open in new window

0
 
LVL 1

Author Comment

by:thready
ID: 40302150
all good answers, thanks everyone- I'm on the right track.  Although it is overflowing, all the data is in my variable as expected.  I will be back soon with points!  :)

The conversion to 3211616289 made me very happy  :o)
0
 
LVL 37

Assisted Solution

by:zzynx
zzynx earned 100 total points
ID: 40302815
And if you know the insides
(
  - the maximum number that fits in an int is Integer.MAX_VALUE
  - a negative int is in fact a number that is too big to fit in an int
  - a negative int is Integer.MAX_VALUE plus the part that doesn't fit, being the number minus Integer.MAX_VALUE
)
here's yet another way to do it:

long longValue2 = (long)Integer.MAX_VALUE + (long)(intValue - Integer.MAX_VALUE);
System.out.println(longValue2);  // this is printing out 3211616289
0
 
LVL 1

Author Closing Comment

by:thready
ID: 40316107
Thanks everyone, sorry for the late reply!
0
 
LVL 37

Expert Comment

by:zzynx
ID: 40316354
You're welcome.
Thanx 4 axxepting
0

Featured Post

Live: Real-Time Solutions, Start Here

Receive instant 1:1 support from technology experts, using our real-time conversation and whiteboard interface. Your first 5 minutes are always free.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
object oriented programming comparison 5 69
MySQL  on Tomcat 8 44
login form jsp example 2 24
eclipse console opening separately 2 16
Summary: This tutorial covers some basics of pointer, pointer arithmetic and function pointer. What is a pointer: A pointer is a variable which holds an address. This address might be address of another variable/address of devices/address of fu…
Introduction This article is the last of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article covers our test design approach and then goes through a simple test case example, how …
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
The viewer will learn how to user default arguments when defining functions. This method of defining functions will be contrasted with the non-default-argument of defining functions.

786 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question