如何从golang的数组中提取字符？

Question

need to extract the random characters from string

here is what i got:

const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
  b := make([]byte, 1)
for i := range b {
    b[i] = letterBytes[rand.Intn(len(letterBytes))]
}
fmt.Println(string(b))

but it always returns "X" but, i need to return every time new character using rand function. any help would be really appreciated. Thanks.

Answer 1

Start by seeding the pseudorandom number generator. For example,

package main

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

func main() {
    rand.Seed(time.Now().UnixNano())
    const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
    b := make([]byte, 7)
    for i := range b {
        b[i] = letterBytes[rand.Intn(len(letterBytes))]
    }
    fmt.Println(string(b))
}

Output:

jfXtySC

---

The Go Playground

About the Playground

In the playground the time begins at 2009-11-10 23:00:00 UTC (determining the significance of this date is an exercise for the reader). This makes it easier to cache programs by giving them deterministic output.

Therefore, in the Go playground, time.Now().UnixNano() always returns the same value. For a random seed value, run the code on your computer.

---

For any Unicode code point (Go rune),

package main

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

package main

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

func main() {
    rand.Seed(time.Now().UnixNano())
    chars := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ世界!@=")
    r := make([]rune, 50)
    for i := range r {
        r[i] = chars[rand.Intn(len(chars))]
    }
    fmt.Println(string(r))
}

Output:

世QRYSp=@giJMIKly=tXRefjtVkeE!yHhTSQHvLyUYdRNIBbILW