Regular Expression for validate price in decimal - objective-c

Question

I really unable to find any workaround for regular expression to input price in decimal.
This what I want:-
12345
12345.1
12345.12
12345.123
.123
0.123
I also want to restrict digits.
I really created one but not validating as assumed
^([0-9]{1,5}|([0-9]{1,5}\.([0-9]{1,3})))$
Also want to know how is above expression different from the one
^([0-9]{1,5}|([0-9].([0-9]{1,3})))$ thats working fine.
Anyone with good explanation.
"I am using NSRegularExpression - Objective C" if this helps to answer more precisely
- (IBAction)btnTapped {
NSRegularExpression * regex = [NSRegularExpression regularExpressionWithPattern:
#"^\\d{1,5}([.]\\d{1,3})?|[.]\\d{1,3}$" options:NSRegularExpressionCaseInsensitive error:&error];
if ([regex numberOfMatchesInString:txtInput.text options:0 range:NSMakeRange(0, [txtInput.text length])])
NSLog(#"Matched : %#",txtInput.text);
else
NSLog(#"Not Matched : %#",txtInput.text);
}
"I am doing it in a buttonTap method".

Answer 1

This simple one should suit your needs:
\d*[.]?\d+
"Digits (\d+) that can be preceded by a dot ([.]?), which can itself be preceded by digits (\d*)."
Since you're talking about prices, neither scientific notation nor negative numbers are necessary.
Just as a point of interest, here's the one I usually used, scientific notation and negative numbers included:
[-+]?\d*[.]?\d+(?:[eE][-+]?\d+)?
For the new requirements (cf. comments), you can't specify how many digits you want on the first regex I gave, since it's not the way it has been built.
This one should suit your needs better:
\d{1,5}([.]\d{1,3})?|[.]\d{1,3}
"Max 5 digits (\d{1,5}) possibly followed ((...)?) by a dot itself followed by max 3 digits ([.]\d{1,3}), or (|) simply a dot followed by max 3 digits ([.]\d{1,3})".

Answer 2

Let's do this per-partes:
Sign in the beginning: [+-]?
Fraction number: \.\d+
Possible combinations (after sign):
Number: \d+
Fraction without zero \.\d+
And number with fraction: \d+\.\d+
So to join it all together <sign>(number|fraction without zero|number with fraction):
^[+-]?(\d+|\.\d+|\d+\.\d+)$

Answer 3

If you're not restricting the lengths to 5 digits before the decimal and 3 digits after then you could use this:
^[+-]?(?:[0-9]*\.[0-9]|[0-9]+)$
If you are restricting it to 5 before and 3 after max then you'd need something like this:
^[+-]?(?:[0-9]{0,5}\.[0-9]{1,3}|[0-9]{1,5})$
As far as the difference between your regexes goes, the first one limits the length of the number of digits before the decimal marker to 1-5 with and without decimals present. The second one only allows a single digit in front of the decimal pointer and 1-5 digits if there is no decimal.

Answer 4

How about this: ^([+-])?(\d+)?([.,])?(\d+)?$
string input = "bla";
if (!string.IsNullOrWhiteSpace(input))
{
string pattern = #"^(\s+)?([-])?(\s+)?(\d+)?([,.])?(\d+)(\s+)?$";
input = input.Replace("\'", ""); // Remove thousand's separator
System.Text.RegularExpressions.Regex.IsMatch(input, pattern);
// if server culture = de then reverse the below replace
input = input.Replace(',', '.');
}
Edit:
Oh oh - just realized that's where we run into a little bit of a problem if an en-us user uses ',' as thousand's separator....
So here a better one:
string input = "+123,456";
if (!string.IsNullOrWhiteSpace(input))
{
string pattern = #"^(\s+)?([+-])?(\s+)?(\d+)?([.,])?(\d+)(\s+)?$";
input = input.Replace(',', '.'); // Ensure no en-us thousand's separator
input = input.Replace("\'", ""); // Remove thousand's separator
input = System.Text.RegularExpressions.Regex.Replace(input, #"\s", ""); // Remove whitespaces
bool foo = System.Text.RegularExpressions.Regex.IsMatch(input, pattern);
if (foo)
{
bool de = false;
if (de) // if server-culture = de
input = input.Replace('.', ',');
double d = 0;
bool bar = double.TryParse(input, out d);
System.Diagnostics.Debug.Assert(foo == bar);
Console.WriteLine(foo);
Console.WriteLine(input);
}
else
throw new ArgumentException("input");
}
else
throw new NullReferenceException("input");
Edit2:
Instead of going through the hassle of getting the server culture, just use the tryparse overload with the culture and don't resubstitute the decimal separator.
double.TryParse(input
, System.Globalization.NumberStyles.Any
, new System.Globalization.CultureInfo("en-US")
, out d
);