golang 随机数的两种方式

func main() {
    fmt.Println(rand.Intn(100))
    //设置随机数种子，由于种子数值，每次启动都不一样
    //所以每次随机数都是随机的
    rand.Seed(time.Now().UnixNano())
    //随机生成100以内的正整数
    fmt.Println(rand.Intn(100))
}

package main
 
import (
    "crypto/rand"
    "encoding/binary"
    "fmt"
    "time"
)
 
func main() {
    var n int32
    binary.Read(rand.Reader, binary.LittleEndian, &n)
    fmt.Println(n)
}

package main
 
import (
    "fmt"
    "math/rand"
    "time"
)
 
func main() {
    fmt.Println(randomString(6, 0))
}
 
/**
* size 随机码的位数
* kind 0    // 纯数字
       1    // 小写字母
       2    // 大写字母
       3    // 数字、大小写字母
*/
func randomString(size int, kind int) string {
    ikind, kinds, rsbytes := kind, [][]int{[]int{10, 48}, []int{26, 97}, []int{26, 65}}, make([]byte, size)
    isAll := kind > 2 || kind < 0
    rand.Seed(time.Now().UnixNano())
    for i := 0; i < size; i++ {
        if isAll { // random ikind
            ikind = rand.Intn(3)
        }
        scope, base := kinds[ikind][0], kinds[ikind][1]
        rsbytes[i] = uint8(base + rand.Intn(scope))
    }
    return string(rsbytes)
}