The usage of common functions of os library in Go language
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(F * File) .Name () this function returns the name of the file. The function prototype func (f * File) Name () string requires the pointer operation of the file and returns a string.
The copy code is as follows:
Func (f * File) Name () string {return f.name}
Import (
"fmt"
"os"
)
Func main () {
F, _: = os.Open ("1.go")
Fmt.Println (f.Name ()) / / output 1.go
}
(F * File) .Read () this is operated by the pointer of the function. It belongs to the method of * FIlE. The function prototype func (f * File) Read (b [] byte) (n int, err error) inputs the number of bytes read and returns the length of bytes and error information.
The copy code is as follows:
Import (
"fmt"
"os"
)
Func main () {
B: = make ([] byte, 100) / / sets the number of bytes read
F, _: = os.Open ("11.go")
N, _: = f.Read (b)
Fmt.Println (n)
Fmt.Println (string (b [: n])) / / Why is the output n instead of entering 100 directly? The underlying layer is implemented in this way.
/ *
N, e: = f.read (b)
If n
< 0 { n = 0 } if n == 0 && len(b) >0 & & e = = nil {
Return 0, io.EOF
}
, /
/ / so read n if the byte is less than 100
}
(F * File) .ReadAt () the prototype of this function is func (f * File) ReadAt (b [] byte, off int64) (n int, err error) added the subscript, you can customize how much to read.
The copy code is as follows:
Import (
"fmt"
"os"
)
Func main () {
F, _: = os.Open ("11.go")
B: = make ([] byte, 20)
N, _: = f.ReadAt (b, 15)
Fmt.Println (n)
Fmt.Println (string (b [: n]))
}
(F * File) .Readdir () function prototype func (f * File) Readdir (n int) (fi [] FileInfo, err error), we need to open a folder, then set the number of folder files to read, and return the fileinfo information of the file.
The copy code is as follows:
Import (
"fmt"
"os"
)
Func main () {
F, err: = os.Open ("src") / / Open a directory
If err! = nil {
Fmt.Println (err)
}
Defer f.Close ()
Ff, _: = f.Readdir (10) / / sets the number of reads
