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one question about casting

yub huang

Joined: Jun 08, 2002
Posts: 17
Q: In the following code, what are the legal type
types for the variable vari, which is declared on line 2?
1. class C {
2. public ??? vari;
3. public static void main(String[] args) {
4. foo(vari);
5. }
6. static void foo(float f){
7. System.out.println("f=" + f);
8. }
9. }
a) boolean
b) byte
c) char
d) double
e) float
f) int
g) long
h) short
I think the answers are b,c,e,f,h. but the correct answers are b,c,e,f,g,h. I compile the g
answer, it is really ok, I don't know why. Can someone help me?

I want to know
Bin Wang

Joined: Mar 04, 2002
Posts: 5
in g, type long to float is implicit windening conversion,even they have same length. so it is correct.
Bin Wang

Joined: Mar 04, 2002
Posts: 5
sorry, type long to float is implicit windening conversion,even length of long is 64 and float is 32.

Joined: Apr 25, 2002
Posts: 2
The conversion is legal because the 32 bits for a float number are divided into two fields: one for magnititude, one for precision and thus the range of a float number is definitely wider than a long number. But note the conversion may result in the loss of accuracy for some large long number.
Jessica Sant

Joined: Oct 17, 2001
Posts: 4313

"bill wang1965", "yub" and "yuelan"
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subject: one question about casting
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