Regex time greater than 00:00

Question

I’m developing a regex validation using the System.ComponentModel.DataAnnotations and RegularExpression from Asp.net mvc C#, in this regex it is necessary to validate unlimited duration time in hours and the time must be greater than 00:00, that is, values can be accepted from 00:01 within minutes(59) and seconds(59).

I managed to get as far as: \d{1,}:[0-5][0-9]

04:00 -- true
00:01 -- true
00:23 -- true
00:04 -- true
04:00 -- true
01:00 -- true
23:00 -- true
21:00 -- true
1:00  -- true
00:61 -- false
00:00 --> problema
57:59 -- true
123:59 -- true

As this is a form, I am only validating a time and not a set of values, as shown in the following image:

I’d like a little help on how to deny the value 00:00 in this regex. As it is in a Regularexpression in Dataannotations, or linked in my model "Duration", I need it to fit in just one validation:

[RegularExpression("^(\d{1,}:[0-5][0-9])$", ErrorMessageResourceName = "CampoObrigatorio")]
public string Duracao { get; set; }

Answer 1

Use the regular expression ^((?!0+:00)\d{1,}:[0-5][0-9])$

As you can see it’s pretty much the same as yours, with an addition that prevents the match from being "0:00" nor "00:00" and neither "0000:00".

The structure I used is called "Negative Lookahead", what it means:

• Negative = is the negation of what is described
• Lookahead = the direction of the negation, which is forward

So (?!0+:00) means: at this point, when looking forward, it may not be possible to match in 0+:00. Note that this structure is an assertive, it does not consume the characters of the string, and so it is possible to follow with the original regular expression its \d{1,}:[0-5][0-9].

Answer 2

Using the set; and get; in your case you can create a "mixed REGEX", it would be something like:

^(00:[0-5][1-9]|00:[1-5][0-9]|0[1-9]+[:][0-5][0-9]|[1-9]+[:][0-5][0-9])$

Your code should look like this:

[RegularExpression("^(00:[0-5][1-9]|00:[1-5][0-9]|0[1-9]+[:][0-5][0-9]|[1-9]+[:][0-5][0-9])$", ErrorMessageResourceName = "CampoObrigatorio")]
public string Duracao { get; set; }

Explaining the REGEX:

• 00:[0-5][1-9] validates times of type 00:01 until 00:59, does not validate 00:10, 00:20, 00:30, etc, so uses the next rule
• 00:[1-5][0-9] validates times of type 00:10 until 00:59 (validates only type 00:xx then tests the next)
• 0[1-9]+[:][0-5][0-9] validates times above 01:00 until 09:59
• [1-9]+[:][0-5][0-9] validates times above 09:59

---

You can also use to validate larger hours than 00:00 using two different REGEX within the method:

One to check if the time is 00:00:

String horarios = "00:00";
Regex ct1 = new Regex(@"^0+:00$"); //00:00 ou 00000:00 são inválidos
If (!ct1.IsMatch(horarios) {
    //Not found 00:00
} else {
    //Invalid hour
}

And one just to check the schedule:

^\d\d+:\d{2}$

The end result would be something like:

String horarios = "00:00";
Regex ct1 = new Regex(@"^0+:00$"); //00:00 ou 00000:00 são inválidos
Regex ct2 = new Regex(@"^\d+:[0-5][0-9]$");//Valida qualquer horário

If (!ct1.IsMatch(horarios)) {//Se algo como 00:00 ou 00000:00, invalida o código
   If (ct2.IsMatch(horarios)) {
       //Validou
   } else {
       //Hora invalida
   }
} else {
   //Hora invalida
}

Note: As it is not a "list" of times use the sign ^ at the beginning and the $ at the end of the REGEX