Three simple messages can be read out:

• The data transmitted in the mail slot is unidirectional (client - > server)
• It can communicate between processes or between networks
• Small data per transmission (400B)

Thinking analysis:

• The server creates a mail slot and waits for the data to arrive and read
• Client opens mail slot and writes data

The effect of the case is shown in the figure:

Server window and function realization steps:

1. Window building and user-defined ID Name:

1. Associate a variable for the button:
   
2. Double click the receive button to realize the function of receiving data for the server:

m_b.EnableWindow(0);			// Make the button unselectable
m_b.SetWindowText(_T("Reading..."));	// Set the contents of the button

// Create slot / / = =/
HANDLE hmailslot = CreateMailslot(_T("\\\\.\\mailslot\\MyMailslot"),
    0, MAILSLOT_WAIT_FOREVER, NULL);		// Create a mail slot and wait for the data to arrive

if(hmailslot == INVALID_HANDLE_VALUE)	// Determine whether the mail slot is successfully created
{
    m_b.EnableWindow(1);		// Change the button back (can be selected)
    m_b.SetWindowText(_T("Receive"));	// The content has changed back
    AfxMessageBox(_T("CreateMailslot error"));
    return;
}

TCHAR buf[400];		// It is used to receive the data obtained from the mail slot. The maximum can only be 400
ZeroMemory(buf, 400);	// Qing 0

DWORD dwRead;	// Number of data actually read
// Read the contents of the mail slot in the same way as the file
if(!ReadFile(hmailslot, buf, 400, &dwRead, NULL))	
{
    m_b.EnablWindow(1);	// If the reading fails, the button will be restored
    m_b.SetWindowText(_T("Receive"));

    AfxMessageBox(_T("ReadFile error"));
    CloseHandle(hmailslot);	// Failed to read the file, close the handle of the mail slot
    return;
}

SetDlgItemText(IDC_EDIT_DATA, buf); // Put the read into the edit box
CloseHandle(hmailslot);		

m_b.EnableWindow(1);	// Button restore
m_b.SetWindowText(_T("Receive"));

Client window and function realization steps:

1. Interface building and custom control ID:

1. Double click the send button to send data to the client:

// Open the mail slot (the essence of the mail slot is a file) see the code below for the meaning of the parameters
HANDLE hMailslot = CreateFile(_T("\\\\.\\mailslot\\MyMailslot"),
    GENERIC_WRITE, FILE_SHARE_READ, NULL, OPEN_EXISTING,
        FILE_ATTRIBUTE_NPRMAL, NULL);

if(hMailslot == INVALID_HANDLE_VALUE)	// Fail to open mail slot
{
    AfxMessageBox(_T("Open mailslot failed."));
    return 0;
}

TCHAR buf[400];		// Buffer for storing data, the maximum can only be 400
ZeroMemory(buf, 400);	// Qing 0

GetDlgItemText(IDC_EDIT_DATA, buf, 400); // Get data in control
DWORD dwWrite;	// Number of data actually written

if(!WriteFile(hMailslot, buf, 400, &dwWrite, NULL))
{
    CloseHandle(hMailslot);	// Failed to write data, closing handle
    AfxMessageBox(_T("Failed to send data!"));
    return;
}

CloseHandle(hMailslot);	 // Closing handle