# Create and open files
// Create a new file through the following two methods:
func Create(name string) (file *File, err Error)
Create a new file based on the provided file name and return a file object. The default permission is 0666. The returned file object is readable and writeable.
func NewFile(fd uintptr, name string) *File
Create the corresponding file according to the file descriptor and return a file object
// Open the file through the following two methods:
func Open(name string) (file *File, err Error)
This method opens a file named name, but it is read-only, and the internal implementation actually calls OpenFile.
func OpenFile(name string, flag int, perm uint32) (file *File, err Error)
Open a file with name, flag is the way to open it, read only, read and write, etc., perm is the permission
// Write a file
func (file *File) Write(b []byte) (n int, err Error)
Write information of type byte to the file
func (file *File) WriteAt(b []byte, off int64) (n int, err Error)
Start writing information of type byte at the specified location
func (file *File) WriteString(s string) (ret int, err Error)
Write string information to file
// Read the file
func (file *File) Read(b []byte) (n int, err Error)
Read data into b
func (file *File) ReadAt(b []byte, off int64) (n int, err Error)
Start reading data into b from off
// Delete the file
func Remove(name string) Error
Call this function to delete a file with the file name
//// Close the file
func (file *File)Close()
Write a file
// code_034_os_write_to_file project
package main
import (
"fmt"
"os"
)
func main() {
// Create a new file fout, err := ("./")
if err != nil {
(err)
return
}
defer ()
for i := 0; i < 5; i++ {
//Note: In Windows environment, the ending \r\n can be opened, and under linux\n can be used outstr := ("%s:%d\r\n", "Hello Go", i) //Sprintf console output and return value string // Write to the file (outstr) //string information ([]byte("abcd\r\n")) //byte type }
}
Read the file
// code_035_os_read_from_file project
package main
import (
"fmt"
"os"
)
func main() {
fin, err := ("./open_and_read1.txt")
if err != nil {
(err) //If the file does not exist: The system cannot find the file specified. }
defer ()
buf := make([]byte, 1024) //Create a storage slice for {
n, _ := (buf) //Read the file if n == 0 {
break
}
(string(buf))
}
}
Copy the file ----》 (Note: local_copy_file.txt that has been created and written) The terminal switches to the current directory and executes go run local_copy_file.txt dst_file.txt
// code_036_os_copy_file project
package main
import (
"fmt"
"io"
"os"
)
func main() {
// Use the command line to improve copy reusability args :=
if args == nil || len(args) != 3 {
("useage : go src File dstFile")
return
}
srcPath := args[1]
dstPath := args[2]
("srcPath = %s, dstPath = %s\r\n", srcPath, dstPath)
if srcPath == dstPath {
("The source file and the target file cannot be renamed")
}
//Execute copy srcFile, err1 := (srcPath)
if err1 != nil {
(err1)
return
}
dstFile, err2 := (dstPath)
if err2 != nil {
(err2)
return
}
read_buf := make([]byte, 1024)
for {
//Read the file n, err := (read_buf) //The length of bytes is read per file if err != nil && err != {
(err)
break
}
if n == 0 {
("File processing is complete")
break
}
//Write to the destination file
write_buf := read_buf[:n]
(write_buf)
}
// Close the file ()
()
}