First of all, you cannot expect receiving Integer type every time. It is very likely that a user of your FLL may pass a numeric parameter not as integer 1 but as a float 1.0. In such a case, ev_long becomes useless.

In my FLLs I pass all numeric input parameters through the following conversion function.

long GetParmLong(Value p)
//accepts float and int, returns int
{
	if ( p.ev_type == 'N' ) return (int)p.ev_real;
	else if ( p.ev_type == 'I' ) return p.ev_long;
	else return 0;
}

So for example, for an external declaration

FoxInfo myFoxInfo[] = 
{
     ...
     {"PD_SETPROGRESS",  (FPFI) SetProgress,  2, "N.N"},
     ...
}

The function is implemented as follows. Note that I also check if the second parameter (declared as optional) exists, otherwise it is replaced with a default value 100.

void SetProgress( ParamBlk *parm )
{
	long dwCompleted = GetParmLong( parm->p[0].val );

	long dwTotal = parm->pCount > 1 
		? GetParmLong( parm->p[1].val ) : 100;

        // ... the rest of code
}