io.PipeWriter.Write() Function in Golang with Examples
Last Updated :
10 May, 2020
In Go language, io packages supply fundamental interfaces to the I/O primitives. And its principal job is to enclose the ongoing implementations of such king of primitives. The PipeWriter.Write() function in Go language is used to implement the standard interface of the Write. It writes information to the pipe and blocks it until one reader or more than one reader has taken up all the information or the read end of the pipe is closed. Moreover, this function is defined under the io package. Here, you need to import the “io” package in order to use these functions.
Syntax:
func (w *PipeWriter) Write(data []byte) (n int, err error)
Here, “w” is a pointer to the PipeWriter. Where PipeWriter is the write half of the pipe and “data” is a byte slice where the data is written.
Return value: It returns the number of bytes written and an error if any. However, if the read end of the pipe is closed with an error then that error is returned as err else the err returned is an ErrClosedPipe error.
Example 1:
package main
import (
"fmt"
"io"
)
func main() {
pipeReader, pipeWriter := io.Pipe()
data := make([]byte, 20)
go func() {
pipeReader.Read(data)
pipeReader.Close()
}()
for i := 0; i < 1; i++ {
n, err := pipeWriter.Write([]byte( "GfG!" ))
if err != nil {
panic(err)
}
fmt.Printf( "%v\n" , string(data))
fmt.Printf( "%v\n" , n)
}
}
|
Output:
GfG!
4
Here, no error is returned as the read end of the pipe is not closed till the “for” loop runs.
Example 2:
package main
import (
"fmt"
"io"
)
func main() {
pipeReader, pipeWriter := io.Pipe()
data := make([]byte, 20)
go func() {
pipeReader.Read(data)
pipeReader.Close()
}()
for i := 0; i < 2; i++ {
n, err := pipeWriter.Write([]byte( "GfG!" ))
if err != nil {
panic(err)
}
fmt.Printf( "%v\n" , string(data))
fmt.Printf( "%v\n" , n)
}
}
|
Output:
GfG!
4
panic: io: read/write on closed pipe
goroutine 1 [running]:
main.main()
/tmp/sandbox367087659/prog.go:38 +0x3ad
Here, an ErrClosedPipe error is returned as the read end of the pipe is closed after the first iteration of the for loop.
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