This example handles the client side of a pipe. It opens an existing named pipe, sends a message to the host, and reads the host reply using the DosTransactNP function.

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     outmsg[256]            = "";         /* Output message buffer */
   CHAR     inmsg[256]             = "";         /* Input message buffer */
   HFILE    PipeHandle             = NULLHANDLE; /* Pipe handle */
   PIPEINFO PipeBuffer[4]          = {{0}};
   struct   _AVAILDATA  BytesAvail = {0};
   UCHAR    Buffer[200]            = {0};
   ULONG    bytes                  = 0;
   ULONG    Action                 = 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");

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

   fflush(NULL);   /* Force above printf to output device */
   gets(outmsg);

   rc = DosTransactNPipe(PipeHandle,          /* Handle of duplex pipe */
                         outmsg,              /* Output message buffer */
                         strlen(outmsg),      /* Size of output message */
                         inmsg,               /* Input message buffer */
                         sizeof(inmsg),       /* SIze of input buffer */
                         &bytes);             /* Number of bytes read */
   if (rc != NO_ERROR) {
      printf("DosTransactNPipe error: error code = %u\n", rc);
      return 1;
   }

   printf("\nMessage received from PIPEHOST: %s\n\n", inmsg);

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