Kotlin将数分解为2的幂
Kotlin将数分解为2的幂
提问于 2019-08-15 17:57:16
嗨，我正在用kotlin编写一个应用程序，需要将一个数字分解为2的幂。
我已经在c#、PHP中这样做了，但是kotlin的工作方式有所不同。
在研究了这一点之后，我相信这与代码中的数字在某个地方变成负数有关，解决方案在于将一个或多个变量声明为“长”，以防止这种情况发生，但我一直无法找到如何做到这一点。
这是我的代码：
var salads = StringBuilder()
var value = 127
var j=0
while (j < 256) {
var mask = 1 shl j
if(value != 0 && mask != 0) {
salads.append(mask)
salads.append(",")
}
j += 1
}
// salads = (salads.dropLast()) // removes the final ","
println("Salads = $salads")这个输出应该是: 1,2,4,8,16,32,64我实际得到的是：
1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,134217728,268435456,536870912,1073741824,-2147483648,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,134217728,268435456,536870912,1073741824,-2147483648,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,134217728,268435456,536870912,1073741824,-2147483648,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,134217728,268435456,536870912,1073741824,-2147483648,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,134217728,268435456,536870912,1073741824,-2147483648,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,134217728,268435456,536870912,1073741824,-2147483648,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,134217728,268435456,536870912,1073741824,-2147483648,1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432,67108864,134217728,268435456,536870912,1073741824,-2147483648,有什么想法吗？
Stack Overflow用户
发布于 2019-08-16 01:34:11
您可以获得适合于Int的所有两个幂的列表，并测试每个幂函数是否包含infix函数and。
val value = 126
val powersOfTwo = (0 until Int.SIZE_BITS).map { n -> 1 shl n }
println(powersOfTwo.filter { p -> value and p != 0}.joinToString(","))
// prints: 2,4,8,16,32,64查看Kotlin操场上的全部代码：https://pl.kotl.in/f4CZtmCyI
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/57514070
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