Right, but the most significant bit (bit 31, the first bit) is always used for the sign.
When bit 31 is a "1" then the value is negative.

cheers

>2 to the zero power through 2 to the 31st power is 32 bits.
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>
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>>>A full 32-bit number (32 one's in a binary number) equals 2 GB, so numbers based on 32-bits cannot address address space beyond 2 GB.
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>>A full 32-bit number (2^32 - unsigned integer) is equal 4G. 2GB can be represented by 31-bit number (2^31).