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Problem with Conversion

 
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Problem

Consider the following code:



Options

Select 1 correct option.



Ans: It will not print 0.

Doubt: how is that happening? I compiled and checked it is giving -46, but how?

Source: (Question ID: 1118) Enthuware

Thanks,
Gitesh
 
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Try the following:
int i = 1234567890;
float f = i;
System.out.println(i);
System.out.println(f);
System.out.println((int)f);

output: 1234567890
1.23456794E9
1234567936

When you do System.out.println(i-(int)f) it will print -46.Since the value of the integer falls out of the range of Integers, it looses its precision from widening and shortening conversions.
 
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I think I figured this one out

1234567890 in binary = 1001001100101100000001011010010
truncated to fit 8-bit exponent for floating point representation = 11010010
negative so flip bits and add 1 = 00101110

et voila -46.

Is this correct? I'm studying for SCJP5 so I haven't covered this stuff in any detail this is an educated guess...
 
Paul Brabban
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I get it thanks Sri Karr
 
Gitesh Ramchandani
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My concern here is that, how to get the value of f, without compiling?

int i = 1234567890;
float f = i;
System.out.println(i);
System.out.println(f);
System.out.println((int)f);

output: 1234567890
1.23456794E9
1234567936

Any help?

Regards,
Gitesh
 
Sri Karr
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You do not need to worry about the exact answer for this. As the exam doesn't test our mathematical skills.
We knew that when we convert a large integer (which has the value out of its range -32768 to 32767)to float the value is going to change slightly.And when we convert the float to integer for the same it is going to loose its precision.(Narrowing conversion).

When we look at the answers for the above question:

1) It will print 0.


2) It will not print 0.


3) It will not compile.


4) It will throw an exception at runtime.


5) None of the above.

we knew that definitely it won't print "0" as the number is large, the conversion changes the number slightly, eliminate 1st option, the code is perfectly fine, so eliminate 3 and 4 th options. You need to choose from options 2nd and 5th.

You knew that if code compiles and doen't throw runtime exception, it will print some number and in this case it won't be "0".so please select 2nd as your answer.
(I guess this question is kind of logical thinking question rather than pure technical questions).
 
Gitesh Ramchandani
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Thanks Sri Karr
 
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