This example handles the client side of a pipe. It opens an existing named pipe and event semaphore, sends a message to the host, reads the host reply, queries the post count of the event semaphore and finally closes the event semaphore and pipe.

Before running this example, compile and run the example code shown in the DosConnectNPipe, DosCreateNPipe, DosDisConnectNPipe, or DosSetNPipeSem functions, which handles the host side of the pipe.

#define INCL_DOSFILEMGR       /* DOS File Manager values */
#define INCL_DOSNMPIPES       /* DOS Named Pipes values */
#define INCL_DOSSEMAPHORES    /* DOS Semaphore values */
#define INCL_DOSERRORS        /* DOS Error values */
#include <os2.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(VOID) {
   APIRET   rc                     = NO_ERROR;   /* Return code */
   CHAR     message[256]           = "";         /* Message buffer */
   HFILE    PipeHandle             = NULLHANDLE; /* Pipe handle */
   HEV      hev                    = NULLHANDLE; /* Event semaphore handle */
   PIPEINFO PipeBuffer[4]          = {{0}};
   struct   _AVAILDATA  BytesAvail = {0};
   UCHAR    Buffer[200]            = {0};
   ULONG    bytes                  = 0;
   ULONG    Action                 = 0;
   ULONG    ulPostCt               = 0;
   int      i                      = 0;
   PIPESEMSTATE infobuf[3]         = {{0}};

   rc = DosOpen("\\PIPE\\EXAMPLE", &PipeHandle, &Action, 0, 0, FILE_OPEN,
                OPEN_ACCESS_READWRITE | OPEN_SHARE_DENYREADWRITE |
                OPEN_FLAGS_FAIL_ON_ERROR, NULL);
   if (rc != NO_ERROR) {
      printf("DosOpen error: error code = %u\n", rc);
      return 1;
   }  else printf("Connected to Pipe.\n");

   rc = DosOpenEventSem("\\SEM32\\PIPE\\EXAMPLE", &hev);
   if (rc != NO_ERROR) {
      printf("DosOpenEventSem error: error code = %u\n", rc);
      return 1;
   }

   printf("Enter message to send to PIPEHOST: ");

   fflush(NULL);  /* Make printf appear on display */
   gets(message);

   rc = DosWrite(PipeHandle, message, strlen(message), &bytes);
   if (rc != NO_ERROR) {
      printf("DosWrite error: error code = %u\n", rc);
      return 1;
   }
   rc = DosRead(PipeHandle, message, sizeof(message), &bytes);
   if (rc != NO_ERROR) {
      printf("DosRead error: error code = %u\n", rc);
      return 1;
   }

   printf("\nMessage received from PHOST: %s\n\n", message);

   rc = DosQueryEventSem(hev, &ulPostCt);
   if (rc != NO_ERROR) {
      printf("DosQueryEventSem error: return code = %u\n", rc);
      return 1;
    } else printf("Current post count value is %u\n", ulPostCt);

   rc = DosCloseEventSem(hev);
   if (rc != NO_ERROR) {
      printf("DosCloseEventSem error: error code = %u\n", rc);
      return 1;
   }

   printf("...Disconnected\n");
   return NO_ERROR;
}