On Sun, Nov 12, 2017, 10:11 PM <2891132l...@gmail.com> wrote:
> So how to modify my program correctly??I try to add read in different
> place but it still can't get the result I want.
>
Make sure your server is doing:
read, write, read, write
And your client is doing:
write, read, write, read
But honestly it becomes hard to keep track and line up the two when you are
complicating the server handler loop. Why not just simplify the server so
that it always just reads, checks the value and writes something back, then
loops again? And the client would make sure to always write and then read.
You have a conditional write on the server so that means if a client
doesn't say the correct phrase, it won't know if reading afterwards is
going to block forever.
> 在 2017年11月12日星期日 UTC+8上午5:05:49，Justin Israel写道：
>>
>>
>>
>> On Sun, Nov 12, 2017, 10:03 AM Justin Israel <justin...@gmail.com> wrote:
>>
>
>>>
>>> On Sat, Nov 11, 2017, 9:55 PM <28911...@gmail.com> wrote:
>>>
>>>> this is the server program：
>>>>
>>>>> package main
>>>>>
>>>>> import (
>>>>> "fmt"
>>>>> "net"
>>>>> "os"
>>>>>
>>>> "strings"
>>>>> )
>>>>>
>>>>> func main() {
>>>>>
>>>>> listener, err := net.Listen("tcp", "0.0.0.0:400")
>>>>>
>>>> checkError(err)
>>>>> for i := 0; i < 10; i++ {
>>>>> conn, err := listener.Accept()
>>>>> if err != nil {
>>>>> continue
>>>>> }
>>>>> handleClient(conn)
>>>>> conn.Close()
>>>>> }
>>>>> }
>>>>> func handleClient(conn net.Conn) {
>>>>> var buf [512]byte
>>>>> for {
>>>>> n, err := conn.Read(buf[0:])
>>>>> if err != nil {
>>>>> return
>>>>> }
>>>>> rAddr := conn.RemoteAddr()
>>>>> fmt.Println("receive from client", rAddr.String(), string(buf[0:n]))
>>>>>
>>>> n, err2 := conn.Write([]byte("welcome client!"))
>>>>>
>>>> if err2 != nil {
>>>>> return
>>>>> }
>>>>>
>>>> aa := string("nice to meet you")
>>>>> if strings.Contains(string(buf[0:n]), aa) {
>>>>> n, err2 = conn.Write([]byte("nice to meet you too"))
>>>>>
>>>> if err2 != nil {
>>>>> return
>>>>> }
>>>>> }
>>>>> }
>>>>> }
>>>>> func checkError(err error) {
>>>>> if err != nil {
>>>>> fmt.Fprintf(os.Stderr, "fatal error: %s", err.Error())
>>>>> os.Exit(1)
>>>>> }
>>>>> }
>>>>>
>>>>
>>>>>
>>>> this is the client program:
>>>> package main
>>>>
>>>> import (
>>>> "fmt"
>>>> "net"
>>>> "os"
>>>> )
>>>>
>>>> func main() {
>>>> var buf [512]byte
>>>> if len(os.Args) != 2 {
>>>> fmt.Fprintf(os.Stderr, "usage:%s host:port\n", os.Args[0])
>>>> }
>>>> _, err := net.ResolveTCPAddr("tcp", "127.0.0.1:400")
>>>> checkError(err)
>>>> conn, err := net.Dial("tcp", "127.0.0.1:400")
>>>> checkError(err)
>>>> rAddr := conn.RemoteAddr()
>>>> n, err := conn.Write([]byte("hello server!"))
>>>> checkError(err)
>>>> n, err = conn.Write([]byte(" nice to meet you"))
>>>> checkError(err)
>>>> n, err = conn.Read(buf[0:])
>>>> if err != nil {
>>>> return
>>>> }
>>>> checkError(err)
>>>> fmt.Println("reply from server", rAddr.String(), string(buf[0:n]))
>>>> conn.Close()
>>>> os.Exit(0)
>>>> }
>>>> func checkError(err error) {
>>>> if err != nil {
>>>> fmt.Fprintf(os.Stderr, "fatal error: %s", err.Error())
>>>> os.Exit(1)
>>>> }
>>>> }
>>>>
>>>>
>>>> Just a little change and I run it successfully.But I am doubt why it
>>>> can't print "nice to meet you too"?？And how to solve it??
>>>>
>>>
>>> Your server does the following on a new connection
>>>
>>> n, err := conn.Read(buf[0:])
>>> ...
>>> n, err2 := conn.Write([]byte("welcome client!"))
>>>
>>> Then your client is doing the following on the start of the connection
>>>
>>> n, err := conn.Write([]byte("hello server!"))
>>> ...
>>>
>>> n, err = conn.Write([]byte(" nice to meet you"))
>>>
>>> Both the client and server are blocking on writing and no one is doing
>>> any reading. Make sure your client does a read after elderly
>>>
>>
>> Thanks autocorrect. I have no problem with the elderly, but it has no
>> business here in this response.
>>
>> successful write, if you are choosing to do a request/reply pattern.
>>>
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