publish lancet

random/random.go

@@ -0,0 +1,50 @@
+// Copyright 2021 dudaodong@gmail.com. All rights reserved.
+// Use of this source code is governed by MIT license.
+
+// Package random implements some basic functions to generate random int and string.
+package random
+
+import (
+	crand "crypto/rand"
+	"io"
+	"math/rand"
+	"time"
+)
+
+// RandString generate random string
+// see https://stackoverflow.com/questions/22892120/how-to-generate-a-random-string-of-a-fixed-length-in-go
+func RandString(length int) string {
+	const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+	b := make([]byte, length)
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	for i := range b {
+		b[i] = letters[r.Int63()%int64(len(letters))]
+	}
+	return string(b)
+}
+
+// RandInt generate random int between min and max, maybe min,  not be max
+func RandInt(min, max int) int {
+	if min == max {
+		return min
+	}
+	if max < min {
+		min, max = max, min
+	}
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	return r.Intn(max-min) + min
+}
+
+// RandBytes generate random byte slice
+func RandBytes(length int) []byte {
+	if length < 1 {
+		return nil
+	}
+	b := make([]byte, length)
+
+	if _, err := io.ReadFull(crand.Reader, b); err != nil {
+		return nil
+	}
+	return b
+}