vscnprintf — Format a string and place it in a buffer
| int vscnprintf ( | char * buf, | 
| size_t size, | |
| const char * fmt, | |
| va_list args ); | 
bufThe buffer to place the result into
sizeThe size of the buffer, including the trailing null space
fmtThe format string to use
argsArguments for the format string
   The return value is the number of characters which have been written into
   the buf not including the trailing '\0'. If size is == 0 the function
   returns 0.
   
   If you're not already dealing with a va_list consider using scnprintf.
   
   See the vsnprintf documentation for format string extensions over C99.