In Vb how to add look behind in Regular Expression

Question

As per my requirement i need to check three conditions using regular expression.

'Find the dot position

 dotPos = InStr(editFormat, ".")

'Find whole number of digits

 wholeNum = Left$(editFormat, dotPos - 1)

'Find decimal number of digits

decNum = Mid(editFormat, dotPos + 1, strLen - dotPos - 1)

regularExp = "^[-]{0,1}[0-9]{0," & wholeNum & "}\" & DecSep & "[0-9]{0," & decNum & "}$"

Here, i need to validate

1) whole value(Before dot)

2) decimal value(After dot)

3) whole length of the input.

wholeNum = 30

decNum  = 20

Ex: The value is 123456789012345678901234567890.12345678901234567890

As per my code this two conditions are working Fine.

But i need to add one more condition is Total length should be 40.

Ex: Possible inputs for your example: ( (30.10) or (20.20) or (25.15) )

1) 123456789012345678901234567890.1234567890 (Total should be 40)

2) 12345678901234567890.12345678901234567890

3) 1234567890123456789012345.678901234567890

How to add that condition in my code.

Thanks.

try **[0-9]*** to match 0 or more times (OR) **[0-9]+** to should match 1 or more times. In your regular expression. — Thirusanguraja Venkatesan, Oct 29 '13 at 14:21

score 0 · Answer 1 · answered Oct 29 '13 at 10:43

0

I'd use a lookahead assertion:

regularExp = "^" & "(?=.{40}$)" & "[-]{0,1}[0-9]{0," & wholeNum & "}\" & DecSep & "[0-9]{0," & decNum & "}$"

assuming you're counting including the dot.

answered Oct 29 '13 at 10:43

Andrew Cheong

1 Answers1