In this article, We are going to see how to write into a file in go with example in details.
We can do it by using either WriteString() or WriteAt() or Write() or WriteFile() function in os package in go golang.
WriteString() function
Function prototype:
func (f *File) WriteString(str string) (n int, err error)
Input Parameter:
str : file name
WriteString() function writes the string into file.
Return value:
WriteString() function in os package returns
the number of bytes written and an error, if any.
Example with code:
package main
import (
"fmt"
"os"
"log"
)
func main() {
file_name := "/Users/hello.go"
file, err := os.Create(file_name)
if err != nil {
log.Fatal(err)
os.Exit(-1)
}
var bytes int
bytes, err = file.WriteString("Hello Go")
if err != nil {
log.Fatal(err)
os.Exit(-1)
}
fmt.Println("Bytes Written in file: ", bytes)
defer file.Close()
}
Output:
$ sudo go run sample.go
Bytes Written in file: 8
$ ls -lrt hello.go
-rw-r--r-- 1 root staff 8 May 5 20:22 hello.go
$cat hello.go
Hello Go
Write() function
Function prototype:
func (f *File) Write(b []byte) (n int, err error)
b: String to be written in byte array
Write() writes len(b) bytes to the File.
Return value:
Write() function in os package returns
the number of bytes written and an error, if any.
Example with code:
package main
import (
"fmt"
"os"
"log"
)
func main() {
file_name := "/Users/hello.go"
file, err := os.Create(file_name)
if err != nil {
log.Fatal(err)
os.Exit(-1)
}
str := []byte("Hello Go")
var bytes int
bytes, err = file.Write(str)
if err != nil {
log.Fatal(err)
os.Exit(-1)
}
fmt.Println("Bytes Written in file: ", bytes)
defer file.Close()
}
Output:
$ sudo go run sample.go
Bytes Written in file: 8
$ ls -lrt hello.go
-rw-r--r-- 1 root staff 8 May 5 20:22 hello.go
$cat hello.go
Hello Go
WriteFile() Function
Function prototype:
func WriteFile(filename string, data []byte, perm os.FileMode) error
Return value:
WriteFile() function in ioutil package returns
an error, if any.
Example with code:
package main
import (
"io/ioutil"
"log"
)
func main() {
file_name := "/Users/hello.go"
data := []byte("Hello go")
err := ioutil.WriteFile(file_name, data, 0644)
if err != nil {
log.Fatal(err)
}
}
Output:
$ sudo go run sample.go
$ ls -lrt hello.go
-rw-r--r-- 1 root staff 5 May 6 19:05 hello.goo
$cat hello.go
Hello
To learn more about golang, Please refer given below link:
https://www.techieindoor.com/go-lang-tutorial/
References:
https://golang.org/doc/
https://golang.org/pkg/