如何为无符号整数类型指定可表示的最大值?
我想知道如何在下面的循环中初始化min，迭代计算一些结构的min和max长度。
var minLen uint = ???
var maxLen uint = 0
for _, thing := range sliceOfThings {
if minLen > thing.n { minLen = thing.n }
if maxLen < thing.n { maxLen = thing.n }
}
if minLen > maxLen {
// If there are no values, clamp min at 0 so that min <= max.
minLen = 0
}
使第一次通过比较，minLen >= n。
当前回答
MaxInt8 = 1<<7 - 1
MinInt8 = -1 << 7
MaxInt16 = 1<<15 - 1
MinInt16 = -1 << 15
MaxInt32 = 1<<31 - 1
MinInt32 = -1 << 31
MaxInt64 = 1<<63 - 1
MinInt64 = -1 << 63
MaxUint8 = 1<<8 - 1
MaxUint16 = 1<<16 - 1
MaxUint32 = 1<<32 - 1
MaxUint64 = 1<<64 - 1
其他回答
我一直记得的方法是，取比特(int8是8位，int是 32位)，除以8，你得到字节(int8将是一个字节，int 应该是四个字节)。
每个字节都是0xFF(有符号整数除外，在这种情况下是最有效的 字节将是0x7F)。结果如下:
package main
func main() {
{
var n int8 = 0x7F
println(n) // 127
}
{
var n uint8 = 0xFF
println(n) // 255
}
{
var n int = 0x7FFF_FFFF
println(n) // 2147483647
}
{
var n uint = 0xFFFF_FFFF
println(n) // 4294967295
}
}
使用数学包中定义的常量:
const (
MaxInt8 = 1<<7 - 1
MinInt8 = -1 << 7
MaxInt16 = 1<<15 - 1
MinInt16 = -1 << 15
MaxInt32 = 1<<31 - 1
MinInt32 = -1 << 31
MaxInt64 = 1<<63 - 1
MinInt64 = -1 << 63
MaxUint8 = 1<<8 - 1
MaxUint16 = 1<<16 - 1
MaxUint32 = 1<<32 - 1
MaxUint64 = 1<<64 - 1
)
来自数学库:https://github.com/golang/go/blob/master/src/math/const.go#L39
package main
import (
"fmt"
"math"
)
func main() {
fmt.Printf("max int64: %d\n", math.MaxInt64)
}
https://groups.google.com/group/golang-nuts/msg/71c307e4d73024ce?pli=1
相关部分:
由于整数类型使用二补运算，因此可以推断 int和uint的最小/最大常量值。例如, const maxint = ^uint(0) const MinUint = 0 const MaxInt = int(MaxInt >> 1) const MinInt = - maxint - 1
根据@CarelZA的评论:
uint8 : 0 to 255
uint16 : 0 to 65535
uint32 : 0 to 4294967295
uint64 : 0 to 18446744073709551615
int8 : -128 to 127
int16 : -32768 to 32767
int32 : -2147483648 to 2147483647
int64 : -9223372036854775808 to 9223372036854775807
MaxInt8 = 1<<7 - 1
MinInt8 = -1 << 7
MaxInt16 = 1<<15 - 1
MinInt16 = -1 << 15
MaxInt32 = 1<<31 - 1
MinInt32 = -1 << 31
MaxInt64 = 1<<63 - 1
MinInt64 = -1 << 63
MaxUint8 = 1<<8 - 1
MaxUint16 = 1<<16 - 1
MaxUint32 = 1<<32 - 1
MaxUint64 = 1<<64 - 1
