18.7 文件
18.7 文件
（1）如何打开一个文件并读取：
file, err := os.Open("input.dat")
if err != nil {
fmt.Printf("An error occurred on opening the inputfile\n" +
"Does the file exist?\n" +
"Have you got acces to it?\n")
return
}
defer file.Close()
iReader := bufio.NewReader(file)
for {
str, err := iReader.ReadString('\n')
if err != nil {
return // error or EOF
}
fmt.Printf("The input was: %s", str)
}
（2）如何通过切片读写文件：
func cat(f *file.File) {
const NBUF = 512
var buf [NBUF]byte
for {
switch nr, er := f.Read(buf[:]); true {
case nr < 0:
fmt.Fprintf(os.Stderr, "cat: error reading from %s: %s\n",
f.String(), er.String())
os.Exit(1)
case nr == 0: // EOF
return
case nr > 0:
if nw, ew := file.Stdout.Write(buf[0:nr]); nw != nr {
fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n",
f.String(), ew.String())
}
}
}
}