Get Index Of First Alpha-numeric Character

In SQL I need to be able to take a varchar parameter @Area and convert it to a float.

The input values for @Area I can't control. They can range from 6300 to 6,300 SqFt to 1.2 Acres .

So to convert this value to a float I basically look through the string and remove everything that isn't a number or a period. Then I would convert this value to square feet based on how large the number is.


Code:

DECLARE @k int, @Temp VarChar(25), @SqFt Float
SELECT@Temp = @Area
select @Temp

select @k = patindex('%[^0-9. ]%', @Temp)
while @k> 0
begin
select @Temp = replace(@Temp, substring(@Temp, @k, 1), '')
select @k= patindex('%[^0-9. ]%', @Temp)
end

If @Temp = ''
BEGIN
SET @Temp = '0'
END

SELECT @SqFt = Convert(Float, @Temp)

--Distinguish if it was acres or square feet
If (@SqFt > 750.00)
BEGIN
SET @SqFt = @SqFt
END
ELSE
BEGIN
SET @SqFt = (@SqFt * Convert(Float,43560) )
END

SELECT @SqFt



This works great except for one situation, If @Area is something like 6,300 Sq.Ft. . When I run it through the part that removes all non-numeric items and periods, I end up with 6300 .. . So to get around this I want to find the first letter in the string and then remove everything after it. Then take the result and run it through part that removes everything but the numbers and period.

However I can't find away to get the index of the alpha-numeric character and remove everything after it.

Thanks in advance!