/
random.go
62 lines (51 loc) · 1.38 KB
/
random.go
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package util
import (
"math/rand"
"time"
)
var src = rand.NewSource(time.Now().UnixNano())
const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
const (
letterIdxBits = 6 // 6 bits to represent a letter index
letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits
)
func RandomString() string {
rand.Seed(time.Now().UnixNano())
return RandomStringWithLength(RandomIntegerRange(3, 16))
}
func RandomStringWithLength(length int) string {
b := make([]byte, length)
for i, cache, remain := length-1, src.Int63(), letterIdxMax; i >= 0; {
if remain == 0 {
cache, remain = src.Int63(), letterIdxMax
}
if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
b[i] = letterBytes[idx]
i--
}
cache >>= letterIdxBits
remain--
}
return string(b)
}
func RandomInteger() int {
rand.Seed(time.Now().UnixNano())
return rand.Int()
}
func RandomIntegerRange(min, max int) int {
rand.Seed(time.Now().UnixNano())
return rand.Intn(max-min) + min
}
func RandomFloat() float64 {
rand.Seed(time.Now().UnixNano())
return rand.Float64()
}
func RandomFloatRange(min, max float64) float64 {
rand.Seed(time.Now().UnixNano())
return min + rand.Float64()*(max-min)
}
func RandomBoolean() bool {
cache := src.Int63()
return cache&0x01 == 1
}