How to send integer as a string with WriteFile for serialport

I want to send an integer as a string buffer to a serial port with WriteFile. This data value is result from the sensor, this data max has 2 characters.

I have tried to convert with itoa

for example:

 DWORD nbytes;
 int a,b,c;
 a=10;
char *tempa ="";
tempa = itoa(a, tempa,0);
if(!WriteFile( hnd_serial, a, 2, &nbytes, NULL )){MessageBox(L"Write Com Port fail!");return;} 

This code is not working.

Unhandled exception at 0x1024d496 (msvcr100d.dll) in ENVSConfig.exe: 0xC0000094: Integer division by zero.

Also I have tried the suggestion from this website: convert int to string but still does not working to.

Is there any clue to do this?

You are not using itoa properly, you need to allocate space for your string, you need to provide a proper radix (this is where your divide-by-zero error is happening) and finally you need to use the buffer, not your original a value, as the buffer in your write.

Try the following:

DWORD nbytes;
int a,b,c;
a = 10;
char tempa[64];  // Randomly picked 64 characters as the max size
itoa(a, tempa, 10);
if(!WriteFile(hnd_serial, tempa, 2, &nbytes, NULL))
{
    MessageBox(L"Write Com Port fail!");
    return;
}