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Go language has the following methods to clear file contents: Use the ioutil.Truncate function to truncate the file. Use the os.Truncate function to directly operate the file descriptor. Use the ftruncate system call to truncate the file directly.
Go language practice: Several methods of clearing file contents
Clearing file contents is a common operation in Go language. There are several ways to do this.
Use the ioutil.Truncate
function
ioutil.Truncate
function to truncate the file to the specified size. If the specified size is 0, the file is cleared.
package main import ( "fmt" "io/ioutil" "os" ) func main() { f, err := os.OpenFile("test.txt", os.O_RDWR, 0644) if err != nil { fmt.Println(err) return } err = ioutil.Truncate("test.txt", 0) if err != nil { fmt.Println(err) return } fmt.Println("File emptied successfully.") }
Use os.Truncate
function
os.Truncate
function with ioutil.Truncate
Similar, but it operates directly on file descriptors.
package main import ( "fmt" "os" ) func main() { f, err := os.OpenFile("test.txt", os.O_RDWR, 0644) if err != nil { fmt.Println(err) return } err = os.Truncate("test.txt", 0) if err != nil { fmt.Println(err) return } fmt.Println("File emptied successfully.") }
Use ftruncate
system call
ftruncate
system call to truncate the file directly.
package main import ( "fmt" "os" "syscall" ) func main() { f, err := os.OpenFile("test.txt", os.O_RDWR, 0644) if err != nil { fmt.Println(err) return } err = syscall.Ftruncate(int(f.Fd()), 0) if err != nil { fmt.Println(err) return } fmt.Println("File emptied successfully.") }
Practical case
In the following practical case, we use the ioutil.Truncate
function to clear a file:
package main import ( "fmt" "io/ioutil" "os" ) func main() { // 打开一个现有文件 f, err := os.OpenFile("test.txt", os.O_RDWR, 0644) if err != nil { fmt.Println(err) return } // 使用 ioutil.Truncate 清空文件 err = ioutil.Truncate("test.txt", 0) if err != nil { fmt.Println(err) return } // 检查文件是否已清空 fi, err := f.Stat() if err != nil { fmt.Println(err) return } if fi.Size() == 0 { fmt.Println("File emptied successfully.") } else { fmt.Println("File not emptied.") } }
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