JavaScript 中 x|0 如何对数字进行取整？
在我之前的问题的接受答案中 ( 最快的生成方式是什么javascript 中的随机整数？ ），我想知道数字如何通过符号 | 丢失小数位 。
例如：
var x = 5.12042;
x = x|0;
如何将数字降至 5？
更多示例：
console.log( 104.249834 | 0 ); //104
console.log( 9.999999 | 0 ); // 9
In the accepted answer on my earlier question
( What is the fastest way to generate a random integer in javascript? ), I was wondering how a number loses its decimals via the symbol |
.
For example:
var x = 5.12042;
x = x|0;
How does that floor the number to 5?
Some more examples:
console.log( 104.249834 | 0 ); //104
console.log( 9.999999 | 0 ); // 9
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（3）
因为，根据 ECMAScript 规范，按位运算符对每个要计算的表达式调用
ToInt32。请参阅11.10 二元按位运算符：
Because, according to the ECMAScript specifications, bitwise operators call
ToInt32on each expression to be evaluated.See 11.10 Binary Bitwise Operators:
位运算符将其参数转换为整数（请参阅 http://es5.github.com/#x9.5< /a>）。
我知道的大多数语言都不支持这种类型的转换：
$ python -c "1.0|0" Traceback (most recent call last): File "", line 1, in TypeError: unsupported operand type(s) for |: 'float' and 'int' $ ruby -e '1.0|0' -e:1:in `': undefined method `|' for 1.0:Float (NoMethodError) $ echo "int main(){1.0|0;}" | gcc -xc - : In function ‘main’: :1: error: invalid operands to binary | (have ‘double’ and ‘int’)Bitwise operators convert their arguments to integers (see http://es5.github.com/#x9.5).
Most languages I know don't support this type of conversion:
$ python -c "1.0|0" Traceback (most recent call last): File "", line 1, in TypeError: unsupported operand type(s) for |: 'float' and 'int' $ ruby -e '1.0|0' -e:1:in `': undefined method `|' for 1.0:Float (NoMethodError) $ echo "int main(){1.0|0;}" | gcc -xc - : In function ‘main’: :1: error: invalid operands to binary | (have ‘double’ and ‘int’)在执行向下取整时，虽然可以将参数转换为整数，但这不是大多数语言会执行的操作，因为原始类型是浮点数。
在保留数据类型的同时，更好的方法是将指数数字放入尾数并将剩余位归零。
如果您有兴趣，可以查看浮点数的 IEEE 规范。
When doing a
floor, although it would be possible to convert the argument to an integer, this is not what most languages would do because the original type is a floating-point number.A better way to do it while preserving the data type is to go to
exponentdigits into themantissaand zero the remaining bits.If you're interested you can take a look at the IEEE spec for floating point numbers.