是的，无符号整数可以存储大的值。 不，有不同的方式来表示正数和负数。 是的，有符号整数可以包含正数和负数。

(回答第二个问题)通过只使用符号位(而不是2的补码)，你可以得到-0。不太漂亮。

是的，无符号整数可以存储大的值。 不，有不同的方式来表示正数和负数。 是的，有符号整数可以包含正数和负数。

除了第二点，其他都是正确的。有符号整型有许多不同的表示法，有些实现使用第一种，有些使用最后一种，还有一些使用完全不同的表示法。这取决于你所使用的平台。

另一个区别是在不同大小的整数之间进行转换时。

例如，如果你从字节流中提取一个整数(简单来说就是16位)，使用无符号值，你可以这样做:

i = ((int) b[j]) << 8 | b[j+1]

(可能应该强制转换第二个字节，但我猜编译器会做正确的事情)

对于有符号的值，你必须担心符号扩展，并做:

i = (((int) b[i]) & 0xFF) << 8 | ((int) b[i+1]) & 0xFF

为了完整起见，这里只提几点:

this answer is discussing only integer representations. There may be other answers for floating point; the representation of a negative number can vary. The most common (by far - it's nearly universal today) in use today is two's complement. Other representations include one's complement (quite rare) and signed magnitude (vanishingly rare - probably only used on museum pieces) which is simply using the high bit as a sign indicator with the remain bits representing the absolute value of the number. When using two's complement, the variable can represent a larger range (by one) of negative numbers than positive numbers. This is because zero is included in the 'positive' numbers (since the sign bit is not set for zero), but not the negative numbers. This means that the absolute value of the smallest negative number cannot be represented. when using one's complement or signed magnitude you can have zero represented as either a positive or negative number (which is one of a couple of reasons these representations aren't typically used).