签署无签名和副Versa(算术) [英] Signed to Unsigned and Vice Versa (arithmetical)
问题描述
如何将数字从无符号转换为有符号?
How to convert a number from unsigned to signed?
已签名:-32768至32767
无符号:0至65535
signed: -32768 to 32767 unsigned: 0 to 65535
我正在解决JavaScript中的问题。情况是,我有一个例如从0到65535,我想将其转换为合理的有符号值。
I am solving the problem in JavaScript. The situation is that I have a number that goes e.g. from 0 to 65535 and I want to convert it to a reasonable signed value.
例如:65535应该变为-1。
e.g.: 65535 should become -1.
请不要使用任何与位相关的操作,而是使用算术。
Please do not use any bit related operations but something arithmetical.
我想这应该是语言无关的,假设我们使用的数据类型足够大。
I guess this should be language independent assuming that we use a data type that is big enough.
更新:
根据答案进一步实施:
Update: Implementation according to the answer further down:
function convertWordToShort(ival) {
if (isNaN(ival) === false) {
if (ival > 32767) {
ival = ival - 65536;
}
}
return ival;
}
function convertShortToWord(ival) {
if (isNaN(ival) === false) {
if (ival < 0) {
ival = ival + 65536;
}
}
return ival;
}
function convertIntToDWord(ival) {
if (isNaN(ival) === false) {
if (ival < 0) {
ival = ival + 4294967296;
}
}
return ival;
}
function convertDWordToInt(ival) {
if (isNaN(ival) === false) {
if (ival > 2147483647) {
ival = ival - 4294967296;
}
}
return ival;
}
推荐答案
只测试数字是否为超过一半,然后减去模数。
Just test if the number is over halfway, then subtract the modulus.
if(x > 32767) {x = x - 65536;}
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