I was testing a tiny snippet I'd written to format a timespan (e.g., last change 5m23s ago) and kept getting an error I couldn't understand. Every time I try to use the loop variable i directly in a call to ts(), ASP informed me An error occurred...
'the function
function ts(s)
dim m: m = CLng(s \ 60): s = s mod 60
dim h: h = CLng(m \ 60): m = m mod 60
ts = right("00" & h, 2) & "h" & _
right("00" & m, 2) & "m" & _
right("00" & s, 2) & "s"
end function
'the test
for i = 0 to 90000 step 15
' response.write i & ": " & ts(i) & "<br />" 'an error has occurred
dim j: j = i : response.write i & ": " & ts(j) & "<br />" 'works fine
next
What in the world is going on here?
Why does ts(i) create an error every time?
Given that, why does j=i : ts(j) work fine?
It can't be a problem with the variable i, since it works fine with the write call. Here's some other things I tried:
response.write i & ": " 'no problem
'response.write ts(i) 'crashes
'dim x: x = ts(i) 'crashes
dim j: j = i 'no problem
dim x: x = ts(j) 'works
response.write x & "<br />" 'works
'response.write ts(j) & "<br />" 'also works
'response.write i & ": " & ts(j) & "<br />" 'also works
(Finally, I know there's allegedly a way to make IIS display real errors. I'd love to hear how to do that without RDP access to the webserver.)
omegastripes clued me in.
Apparently in VBScript, the default is for parameters to be passed ByReference.
(Literally every other programming language I've ever used passes primitives ByValue)
This caused a problem when I changed the value of s inside the function.
Any of these snippets work just fine:
function ts(ByVal s)
...
...
ts(i)
function ts(sec)
dim s: s = sec
...
...
ts(i)
(or, as mentioned in the OP, passing the value in a non-loop-iterator variable)
function ts(s)
...
dim j: j = i: ts(j)