go的rand.Intn()用法和猜年龄, rand.Int()和字符串反转

rand.Intn()用法和猜年龄

package main

import (
	"fmt"
	"math/rand"
	"time"
)

func init() {
	rand.Seed(time.Now().UnixNano())
}

func main() {
	target := rand.Intn(101)
	count := 0
	cur := -1
	for cur != target {
		fmt.Scanf("%d", &cur)
		count++
		if cur == target {
			fmt.Println("恭喜你，猜对了。")
		} else if cur < target {
			fmt.Println("猜小了。")
		} else {
			fmt.Println("猜大了。")
		}
	}
	fmt.Printf("你一共猜了：%d次\n", count)
}

rand.Int()和字符串反转

package main

import (
	"fmt"
	"math/rand"
	"time"
)

func init() {
	rand.Seed(time.Now().UnixNano())
}

func reverse(str string) string {
	
	/*
	//方式一
	var result string
	strLen := len(str)
	for i := 0; i < strLen; i++ {
		result += fmt.Sprintf("%c", str[strLen-i-1])
	}
	return result
	*/

	/*
	//方式二
	tmp := []byte(str)
	var result string
	for i := len(str)-1; i >= 0; i-- {
		result = result + fmt.Sprintf("%c", tmp[i])
	}
	return result
	*/
	
	//方式三
	var result []byte
	tmp := []byte(str)
	fmt.Printf("你好啊tmp%#v\n", tmp)
	length := len(str)
	for i := 0; i < length; i++ {
		result = append(result, tmp[length-i-1])
	}
	fmt.Printf("你好啊tmp2>>%#v\n", tmp)
	return string(result)
}

func main() {
	for i := 1; i <= 10; i++ {
		fmt.Printf("rand.Int()=%d,i=%d>>\n",rand.Int(),i)
		fmt.Printf("rand.Intn(100)=%d,i=%d>>\n",rand.Intn(100),i)
		fmt.Printf("rand.Float32()=%f,i=%d>>\n",rand.Float32(),i)
		fmt.Println()
		//fmt.Println(rand.Float32())
	}

	str := "hello world"
	fmt.Println(reverse(str))
}