Golang：os/io标准库读取文件

$ go version
go version go1.19 darwin/amd64

func os.ReadFile(name string) ([]byte, error)
func os.Open(name string) (*File, error)
func io.ReadAll(r Reader) ([]byte, error)
// Deprecated os.ReadFile
func ioutil.ReadFile(filename string) ([]byte, error)
// Deprecated io.ReadAll
func ioutil.ReadAll(r io.Reader) ([]byte, error)

package main
import (
    "fmt"
    "os"
)
func main() {
    content, err := os.ReadFile("demo.txt")
    if err == nil {
        // 将[]byte 转为 string后输出
        fmt.Println(string(content))
    }
}

package main
import (
    "fmt"
    "io"
    "os"
)
func main() {
    file, err := os.Open("demo.txt")
    if err == nil {
        defer file.Close()
        content, err := io.ReadAll(file)
        if err == nil {
            fmt.Println(string(content))
        }
    }
}