Directory title
- 1. Writing files Writing files
-
- 1. Writing string to a file Writing string
- 2. Writing bytes to a file Writing bytes
- 3. Writing strings line by line to a file
- 4. Appending to a file Adding content
- 5. Writing to file concurrently Writing to file concurrently
- 2. iota constant generator
1. Writing files Writing files
1. Writing string to a file Writing string
package main
import (
"fmt"
"os"
)
func main() {<!-- -->
f, err := os.Create("writing.txt") // Create file
fmt.Println(err)
if err != nil {<!-- --> // Check if there is an error
fmt.Println(err)
return
}
l, err := f.WriteString("Hello, World!") // Write to file
fmt.Println(err)
if err != nil {<!-- --> // Check if there is an error
fmt.Println(err)
f.Close()
return
}
fmt.Println(l, "bytes written successfully")
err = f.Close()
if err != nil {<!-- --> // Check if there is an error
fmt.Println(err)
return
}
}
// <nil>
// <nil>
// 13 bytes written successfully
2. Writing bytes to a file Writing bytes
package main
import (
"fmt"
"os"
)
func main() {<!-- -->
f, err := os.Create("bytes")
if err != nil {<!-- -->
fmt.Println(err)
return
}
d2 := []byte{<!-- -->104, 101, 108, 108, 111, 32, 98, 121, 116, 101, 115}
n, err := f.Write(d2)
if err != nil {<!-- -->
fmt.Println(err)
f.Close()
return
}
fmt.Println(n, "Bytes written successfully")
err = f.Close()
if err != nil {<!-- -->
fmt.Println(err)
return
}
}
\t\t
// 11 Bytes written successfully
3. Writing strings line by line to a file Write string by line
package main
import (
"fmt"
"os"
)
func main() {<!-- -->
f, err := os.Create("Lines")
if err != nil {<!-- -->
fmt.Println(err)
f.Close()
return
}
d := []string{<!-- -->"Welcome to the world of Go1.", "Go is a compiled language.", "It is easy to learn Go."}
for _, v := range d {<!-- -->
fmt.Fprintln(f, v) // Use the fmt.Fprintln() function to write each element to the file
if err != nil {<!-- -->
fmt.Println(err)
return
}
}
err = f.Close()
if err != nil {<!-- -->
fmt.Println(err)
return
}
fmt.Println("File written successfully")
}
// File written successfully
4. Appending to a file Add content
package main
import (
"fmt"
"os"
)
func main() {<!-- -->
f, err := os.OpenFile("lines", os.O_APPEND|os.O_WRONLY, 0644)
if err != nil {<!-- -->
fmt.Println(err)
return
}
newLine := "File handling is easy."
_, err = fmt.Fprintln(f, newLine)
if err != nil {<!-- -->
fmt.Println(err)
f.Close()
return
}
err = f.Close()
if err != nil {<!-- -->
fmt.Println(err)
return
}
fmt.Println("file appended successfully")
}
// File appended successfully
5. Writing to file concurrently Writing to file concurrently
package main
import (
"fmt"
"math/rand"
"os"
"sync"
)
func produce(data chan int, wg *sync.WaitGroup) {<!-- -->
n := rand.Intn(999) // Randomly generate a number within 999 and pass it into the channel
data <- n
wg.Done()
}
func consume(data chan int, done chan bool) {<!-- -->
f, err := os.Create("concurrent") // Create file
if err != nil {<!-- -->
fmt.Println(err)
return
}
for d := range data {<!-- -->
_, err = fmt.Fprintln(f, d) // Loop into files
if err != nil {<!-- --> // If not nil, writing fails
fmt.Println(err)
f.Close()
done <- false // Incoming channel failed
return
}
}
err = f.Close() // Close the file
if err != nil {<!-- -->
fmt.Println(err)
done <- false
return
}
done <- true // close channel
}
func main() {<!-- -->
data := make(chan int)
done := make(chan bool)
wg := sync.WaitGroup{<!-- -->}
for i := 0; i < 100; i + + {<!-- -->
wg.Add(1)
go produce(data, &wg)
}
go consume(data, done)
go func() {<!-- -->
wg.Wait()
close(data)
}()
d := <-done
if d {<!-- -->
fmt.Println("File written successfully")
} else {<!-- -->
fmt.Println("File writing failed")
}
}
// File written successfully
Please see the previous article for reading files
2. iota constant generator
type WeekDay int
const (
Sunday WeekDay = iota
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
)
func main() {<!-- -->
fmt.Println(Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, WeekDay(2))
fmt.Println(WeekDay(0))
day := WeekDay(1)
switch day {<!-- -->
case Sunday:
fmt.Println("Today is Sunday")
case Monday:
fmt.Println("Today is Monday")
case Tuesday:
fmt.Println("Today is Tuesday")
case Wednesday:
fmt.Println("Today is Wednesday")
case Thursday:
fmt.Println("Today is Thursday")
case Friday:
fmt.Println("Today is Friday")
case Saturday:
fmt.Println("Today is Saturday")
default:
fmt.Println("Invalid weekday")
}
}
// 0 1 2 3 4 5 6 2
// 0
// Today is Monday
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