Envoie d une valeur sur le port com

Salut a tous, j ai realise un programme permettant de changer, d incrementer ou de decrementer une variable "Volume"
J arrive a Convertir "Volume" en string, mais je n arrive pas a l envoyer via le port com, car ma fonction Writecom attend que l utilisateur tape quelquechose, moi j aimerais qu elle envoie directement "Volume" en string.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h>
#include <commdlg.h>
#include <math.h>
#include <conio.h>
 
HANDLE g_hCOM = NULL;
 
DCB g_dcb =
   {
       sizeof(DCB), /* DCBlength */
       9600, // BaudRate */
       TRUE, /* fBinary */
       FALSE, /* fParity */
       FALSE, /* fOutxCtsFlow */
       FALSE, /* fOutxDsrFlow */
       DTR_CONTROL_ENABLE, /* fDtrControl */
       FALSE, /* fDsrSensitivity */
       FALSE, /* fTXContinueOnXoff */
       FALSE, /* fOutX */
       FALSE, /* fInX */
       FALSE, /* fErrorChar */
       FALSE, /* fNull */
       RTS_CONTROL_ENABLE, /* fRtsControl */
       FALSE, /* fAbortOnError */
       0, /* fDummy2 */
       0, /* wReserved */
       0x100, /* XonLim */
       0x100, /* XoffLim */
       8, /* ByteSize */
       NOPARITY, /* Parity */
       ONESTOPBIT, /* StopBits */
       0x11, /* XonChar */
       0x13, /* XoffChar */
       '?', /* ErrorChar */
       0x1A, /* EofChar */
       0x10 /* EvtChar */
   };
 
 
	  BOOL OpenCom (int fd);
	  BOOL CloseCom ();
	  BOOL ReadCom (void* buffer, int nBytesToRead, int* pBytesRead);
	  BOOL WriteCom (void* buffer, int nBytesToWritten, int* pBytesWritten);
 
 
	  BOOL OpenCom(int fd)
	  {
		char szCom[16];
 
		sprintf(szCom,"COM%d", fd);
		g_hCOM= CreateFile(szCom, GENERIC_READ|GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_SYSTEM, NULL);
 
		if (g_hCOM == INVALID_HANDLE_VALUE)
		{
			printf("Erreur dóuverture du port COM%d", fd);
			return FALSE;
 
		}
 
	  }
 
 
	  BOOL CloseCom()
		{
			CloseHandle(g_hCOM);
		return TRUE;
	}
 
int main(int argc, char *argv[]) 
{
 
    int nChoice,fd,nBytesWritten;
    float volume;
	volume=0;
 
	char *pointer;
 
    char buffer[256];
 
 
 
	printf("Number of port COM :");
	scanf("%d", &fd);
 
	printf("Configuration of Com%d\r\n");
		if(!OpenCom(fd)) return -1;
		printf("....OK\r\n");
 
    do
    {
 
	/* menu */
          printf("\r\n");
          printf("Hello, what do you want to do?\r\n");
          printf("1 : See the volume.\r\n");
          printf("2 : Change the volume.\r\n");
          printf("3 : Loop inc+.\r\n");
          printf("4 : Loop inc-.\r\n");
          printf("5 : Transmit to COM1.\r\n");
          printf("6 : EXIT.\r\n");
          printf("Your Choice : ");
          scanf("%d", &nChoice);
 
          if(nChoice == 1)
          {
              printf("\r\n");
              printf("The Volume is :%f\r\n", volume);
          }
 
          if(nChoice == 2)
          {
          printf("\r\n");            
          printf("New value for the volume :\n\r");
          scanf("%f", &volume);
          printf("The new volume is : %f\r\n", volume);
          }   
 
 
              if (nChoice == 3)//Robot goes down
          {
          while(volume<201)
                  {
                      printf("volume = %f\n",volume);
                      volume++;
                  }	   
          }    
 
 
			  if (nChoice == 4)//robot goes Up
			  {
			while(volume>-1)
			{
				printf("volume = %f\n", volume);
				volume--;
			}
 
			  }	
 
				if (nChoice == 5)//transmit to COM1
				{
			  printf("\r\n");
			  pointer = (char *)&volume;
			  printf("New Volume to send: %.5f\n", volume);
			  printf("pointer values: %c%c%c%c\n", pointer[0], pointer[1], pointer[2], pointer[3]);
 
			  buffer[256]=*pointer;
 
 
	      fflush(stdin);
              gets(pointer);
              printf("\r\n");
              printf("Sending is running...\n");
              if(WriteCom(pointer, strlen(pointer), &nBytesWritten))
                  printf("%d Octets were send\n", nBytesWritten);
              else
                  printf("Erreur lors de l'envoi.\r\n");
				  }
//erreur lors de l envoie
 
          } 
while(nChoice != 6);
 
      /* fermeture du port COM et retour */
      CloseCom();
      return 0;
}
 
BOOL WriteCom(void* buffer, int nBytesToWrite, int* pBytesWritten)
 {
     /* écriture sur le port */
    return WriteFile(g_hCOM, buffer, nBytesToWrite, (DWORD*)pBytesWritten, NULL);
 }
 
 
//Est Solarus oth Mithas et Tenebrae Non Victix Lux

si quelqun pouvais me dire si il connait une fonction qui envoie une valeur via le port com je le remercie !