let an integer say, x=0xffffff0;
when i shift left 4 positions in it.it got negative. x=x<<1; doing this 4th time,number got negative. please tell why it is so.
gourav1 -12 Posting Whiz in Training
JamesCherrill 4,733 Most Valuable Poster Team Colleague Featured Poster
x=0xffffff0;
That's 7 hex digits, so the full value of your int, in hex is
0F FF FF F0
shifted 4 left that becomes
FF FF FF 00
ints are stored as 1 sign bit (0 = positive, 1 = negative) and 31 bits of value.
So on your 4th shift the first bit changes from 0 to 1 and the int gets interpreted as a negative number.
gourav1 -12 Posting Whiz in Training
x=0xffffff0;
That's 7 hex digits, so the full value of your int, in hex is
0F FF FF F0
shifted 4 left that becomes
FF FF FF 00
ints are stored as 1 sign bit (0 = positive, 1 = negative) and 31 bits of value.
So on your 4th shift the first bit changes from 0 to 1 and the int gets interpreted as a negative number.
hey! please please explain it more. explain each word more properly please.
JamesCherrill 4,733 Most Valuable Poster Team Colleague Featured Poster
Sorry, that's as clear as I can make it. Just read it slowly and check any words you don't understand by looking on Google or Wikipedia
gourav1 -12 Posting Whiz in Training
Sorry, that's as clear as I can make it. Just read it slowly and check any words you don't understand by looking on Google or Wikipedia
okay! please just explain me how is it 0F FF FF F0 ? why u include 0 at the starting of it? my exam is there please explain
stultuske 1,116 Posting Maven Featured Poster
if your exam is about to arrive, I doubt this is the first time you've had the option to study this material.
realise that an int is (normally portrayed as) decimal, that what you want is hexadecimal, take a look at the differences and see if you can find the values with the same values in decimal and hexadecimal for
0F FF FF F0
and for
FF FF FF 00
gourav1 -12 Posting Whiz in Training
Sorry, that's as clear as I can make it. Just read it slowly and check any words you don't understand by looking on Google or Wikipedia
my second question to u is that "when i say int x=0xffffffff"(8 times f) then it prints only -1.okay why it is negative i know it. but why its value is only "1"? it should be greater than 1 means much greater than 1?
JamesCherrill 4,733 Most Valuable Poster Team Colleague Featured Poster
The value part of an int for a negative value is held in "two's compliment" form, in which ffffffff is -1 and 80000000 is the largest possible negative number. It's a bit like inverting all the 1s and 0s for negative numbers, because that makes it much easier to design the hardware for adding numbers. The full story is a bit more complicated, so here's an article that explains it in great detail
http://en.wikipedia.org/wiki/Two%27s_complement
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