The STR(x,l,p) and CAST(x to N(l,p))
should convert a number
to the string representation rounded with decimal p of the number x.

This doesn't happen and when the value is at least .n..n4995 VFP it rounds up.

Repro:

CLEAR
SET POINT TO

z=0.5
y=0.4994
? y,STR(y,10,0),CAST(y as N(10,0)),ROUND(y,0) at 50

x=0.4995
? x,STR(x,10,0),CAST(x as N(10,0)),ROUND(x,0) at 50

x=0.264995
? x,STR(x,10,2),CAST(x as N(10,2)),ROUND(x,2) at 50

x=0.264996
? x,STR(x,10,2),CAST(x as N(10,2)),ROUND(x,2) at 50
 
* the bug is cyclic

SET TEXTMERGE TO "errors.txt" ON NOSHOW

FOR n=0 TO 4
	WAIT WINDOWS "TEST"+STR(N) NOWAIT
	FOR j=MAX(10^(n-1),1) TO MAX(10^n-1,1)
		dd1='0.'+LEFT(TRANSFORM(j),N)+'4'
		FOR k=990 TO 999
			x=VAL(m.dd1+TRANSFORM(K))
			IF STR(x,10,n)==STR(ROUND(x,n),10,n)
				\ <<ROUND(X,N+4)>>
				LOOP
			ENDIF
			\ <<ROUND(X,N+4)>> <<STR(x,10,n)>> <<CAST(X AS N(10,n))>>  <<ROUND(X,N)>>  
		NEXT
		\
	NEXT
NEXT

SET TEXTMERGE TO

MODIFY FILE "errors.txt"

The thing becomes a tragic comedy when is read

http://support.microsoft.com/kb/157954/en-us

On this it is said that ROUND() it is not exact,
and as workaround is used the VAL() of a STR() conversion.


BUG: ROUND() Function Not Rounding Properly After Calculations

RESOLUTION
....
The following code example provides a workaround by converting the numeric contents of mpay to a string.
Then the VAL() function converts the string back to a numeric data type for use in the ROUND() function.
...

But STR() have a round bug!

Then VFP is in short-circuit, and cannot round a number exactly.

Someone can put hand to ROUND(), STR() and CAST().

Thanks.

Fabio