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Complex string compare logic

I need help with some complex (for me anyway as I not too experienced) string comparison logic. Basically, I want to validate a string to make sure it matches a format rule. I am using C#, targeting .NET 4.5.2.
I am trying to work with an API which gives me the expected format of the string this way:
1:420+4:9#### (must have “420” starting in position 1 AND have a “9” in position 4 AND have numeric digits in positions 5-8
2:Z+14:&&+20:10,11,12 (must have a “Z” in position 2 AND and alpha letters in positions 14, 15 AND have either “10”, “11”, or “12” starting in position 20
Legend:
":" = position/valuelist separator
"," = value separator
"+" = test separator
"#" = numeric digit-only wildcard
"&" = alpha letter-only wildcard
Given this, my first thought is to do a series of substrings and splits of the input string and then do compare on each section? Or, I could do a for loop and iterate through each character one by one until I hit the end of the length of the input string.
Let's assume in this case that the input string is something like "420987435744585". Using rule number one, I should get a pass on this since the first three are 420, position 4 is a 9 and the next 5-8 are numeric.
So far, I have created a method that returns a bool if I pass/fail validation. The input string is passed in. I then started to split on + or - to get all of the and or not sections and then split on comma to get the groups of rules. But this is where I am stuck. It seems like it should be easy and maybe it is but I just can't seem to wrap my head around it and I am thinking I am going to end up with a ton of arrays, foreach loops, if statements, etc... Just to validate and return true/false if the input string matches my format.
Can somebody please assist and give some guidance?
Thank you!!!!

The best way to handle these conditions would be using Regular Expressions (Regex). At first, you may find it a bit complicated, but it's worth to put time on learning it to handle all types of string patterns in a simple non-verbose way.
You can start with these tutorials :
http://www.codeproject.com/Articles/9099/The-Minute-Regex-Tutorial
http://www.tutorialspoint.com/csharp/csharp_regular_expressions.htm
And use this one as a reference :
https://msdn.microsoft.com/en-us/library/az24scfc(v=vs.110).aspx

I think the best way is a custom function, it will be faster than RegEx, and it would be a lot of manual work to convert that format to RegEx.
I've made a start at the validation function, and it's testing ok for the samples you provided.
Here is the code:
static bool CheckFormat(string formatString, string value)
{
string[] tests = formatString.Split('+');
foreach(string test in tests)
{
string[] testElement = test.Split(':');
int startPos = int.Parse(testElement[0]);
string patterns = testElement[1];
string[] patternElements = patterns.Split(',');
foreach(string patternElement in patternElements)
{
//value string not long enough, so fail.
if(startPos + patternElement.Length > value.Length)
return false;
for (int i = 0; i < patternElement.Length; i++)
{
switch(patternElement[i])
{
case '#':
if (!Char.IsNumber(value[i]))
return false;
break;
case '&':
if (!Char.IsLetter(value[i]))
return false;
break;
default:
if(patternElement[i] != value[i])
return false;
break;
}
}
}
}
return true;
}
The dotnet fiddle is here if you want to play with it: https://dotnetfiddle.net/52olLQ.
Good luck.

How to pick out specific parts of a text box?

I am trying to pick out specific letters/numbers from a text box, because each means something. After that I am trying to display in a label what it means.
So if I have a number AB-123456, I need to first pick out AB something like:
If (textBox.Text.Substring(0,2) == "AB") {
//Display to a label
}
First off, this doesn't work and I also tried substring(0,1) but also was receiving errors when I used my clear button to clear the text box.
After that I still need to pull the rest of the numbers. The next one I need to pull and define is 123, then 4 by itself, 5 by itself, and six by itself.
How do I go about pulling each of these individually if substring isnt working?

Try this:
if (textBox.Text.StartsWith("AB"))
{
//Display to a label
}
Use this if you don't want to have to check the Length of the text first. Also, you can include a StringComparison argument if you want to ignore case.

string input = textBox.Text;
// check the length before substring
If (input.Length >= 2 && input.Substring(0,2) == "AB") {
//Display to a label
}
or use regex:
string txt="AB-1234562323";
string re="AB-(\\d+)"; // Integer Number 1
Regex r = new Regex(re,RegexOptions.IgnoreCase|RegexOptions.Singleline);
Match m = r.Match(txt);
if (m.Success)// match found
{
// get the number
String number=m.Groups[1].ToString();
}

How to check if a MaskedTextBox is empty from a user input?

I'm using a MaskedTextBox, with the following short date Mask: "00/00/0000".
My problem is that I wanna know when the control is empty:
if (string.IsNullOrEmpty(maskedTextBox1.Text))
{
DataTable dt = function.ViewOrders(Functions.GetEid);
dataGridView2.DataSource = dt;
}
It's not working, when maskedTextBox1 looks empty (and I'm sure it is), the if statement doesn't detect that it is null or Empty.

You can simply use:
maskedTextBox1.MaskCompleted
Or
maskedTextBox1.MaskFull
properties to check if user has entered the complete mask input or not.

I know this is old but I would first remove the mask and then check the text like a normal textbox.
maskedTextBox.TextMaskFormat = MaskFormat.ExcludePromptAndLiterals;
//...Perform normal textbox validation

I just faced this problem. I Needed the Masked Value, but also needed send empty string if the user didn't introduced any data in one single step.
I discovered the property
MaskedTextProvider.ToDisplayString so I use the MaskedTextbox with:
maskedTextBox.TextMaskFormat = MaskFormat.ExcludePromptAndLiterals;
BUT I always read the text from:
maskedTextBox.MaskedTextProvider.ToDisplayString()
This way, if the user has not introduced text in the control Text property will be empty:
maskedTextBox.Text == string.Empty
And when you detect the string is not empty you can use the full text including literals for example:
DoSomething((maskedTextBox.Text == string.Empty) ? maskedTextBox.Text: maskedTextBox.MaskedTextProvider.ToDisplayString());
or
DoSomething((maskedTextBox.Text == string.Empty) ? string.Empty: maskedTextBox.MaskedTextProvider.ToDisplayString());

If you set the property maskedTextBox.TextMaskFormat = MaskFormat.ExcludePromptAndLiterals then the TypeValidationCompleted event validation will not work. To test if the short date maskedtextbox is empty you could just use:
if (maskedTextBox1.Text == " / /")
{
...;
}

Did you try trim.
if(string.IsNullOrEmpty(maskedTextBox.Text.Trim())

What logic are you trying to accomplish with the if statement? As it is right know, you are saying:
If the textbox is empty, set source of datagridview2 + to ViewOrder data. I'm not sure what your trying to do but I think you want the info to load if you have a date. to fix this all you have to do is add ! in the if statement which would make the if statement mean, if there is text in textbox then run code.
if( !(string.IsNullOrEmpty(maskedTextBox2.Text)))

In case of Telerik masked textbox which does not have MaskCompleted or MaskFull, a tricky solution would be this:
the mask always contain a charachter like this: "_" we check masked text box by this:
if (textbox1.Text.Contains("_"))
{
MessageBox.Show("Please enter the correct numbers!","Error",MessageBoxButtons.OK,MessageBoxIcon.Stop);
return;
}
if the text box is full, then it does not contain "_".

I believe the MaskedTextBox, (MTB), using the mask “00/00/0000” is an incorrect string to use for testing its emptiness. This is because the MTB is not like a normal textbox, and the short date mask must be used to determine its string value.
Let’s assume you have a MTB name mskDateOfBirth on your form. In order to test its emptiness, a statement like the following is needed
if (mskDateOfBirth.MaskedTextProvider.ToDisplayString() == "__/__/____")
{
// Do something when true
}
else
{
// Do something when false
}
I have tested this out using Visual Studio 2019 and it works fine. Hope this is helpful.

If the empty value is " / /", declare a constant for it:
const string EmptyDateInput = " / /";
And then later you can repeatedly use it to compare:
if (maskedTextBox1.Text == EmptyDateInput)
{
}

I test this concept and was success in in the following syntax
if( maskedtextbox_name.MaskkedTextProvider.ToDisplayString() == "__-__-____")
{
// Your function;
}

Search for a sub-string within a string

I am really a beginner, I already know
string.indexOf("");
Can search for a whole word, but when I tried to search for e.g: ig out of pig, it doesn't work.
I have a similar string here(part of):
<Special!>The moon is crashing to the Earth!</Special!>
Because I have a lot of these in my file and I just cannot edited all of them and add a space like:
< Special! > The moon is crashing to the Earth! </ Special! >
I need to get the sub-string of Special! and The moon is crashing to the Earth!
What is the simple way to search for a part of a word without adding plugins like HTMLAgilityPack?

IndexOf will work, you are probably just using it improperly.
If your string is in a variable call mystring you would say mystring.IndexOf and then pass in the string you are looking for.
string mystring = "somestring";
int position = mystring.IndexOf("st");

How are you using it? You should use like this:
string test = "pig";
int result = test.IndexOf("ig");
// result = 1
If you want to make it case insensitive use
string test = "PIG";
int result = test.IndexOf("ig", StringComparison.InvariantCultureIgnoreCase);
// result = 1
String.IndexOf Method - MSDN

Please try this:
string s = "<Special!>The moon is crashing to the Earth!</Special!>";
int whereMyStringStarts = s.IndexOf("moon is crashing");
IndexOf should work with spaces too, but maybe you have new line or tab characters, not spaces?
Sometimes case-sensitivity is important. You may control it by additional parameter called comparisonType. Example:
int whereMyStringStarts = s.IndexOf("Special", StringComparison.OrdinalIgnoreCase);
More information about IndexOf: String.IndexOf Method at MSDN
Anyway, I think you may need regular expressions to create better parser. IndexOf is very primitive method and you may stuck in big mess of code.

string page = "<Special!>The moon is crashing to the Earth!</Special!>";
if (page.Contains("</Special!>"))
{
pos = page.IndexOf("<Special!>");
propertyAddress = page.Substring(10, page.IndexOf("</Special!>")-11);
//i used 10 because <special!> is 10 chars, i used 11 because </special!> is 11
}
This will give you "the moon is crashing to the earth!"

Remove formatting from a string: "(123) 456-7890" => "1234567890"?

I have a string when a telephone number is inputted - there is a mask so it always looks like "(123) 456-7890" - I'd like to take the formatting out before saving it to the DB.
How can I do that?

One possibility using linq is:
string justDigits = new string(s.Where(c => char.IsDigit(c)).ToArray());
Adding the cleaner/shorter version thanks to craigmoliver
string justDigits = new string(s.Where(char.IsDigit).ToArray())

You can use a regular expression to remove all non-digit characters:
string phoneNumber = "(123) 456-7890";
phoneNumber = Regex.Replace(phoneNumber, #"[^\d]", "");
Then further on - depending on your requirements - you can either store the number as a string or as an integer. To convert the number to an integer type you will have the following options:
// throws if phoneNumber is null or cannot be parsed
long number = Int64.Parse(phoneNumber, NumberStyles.Integer, CultureInfo.InvariantCulture);
// same as Int64.Parse, but returns 0 if phoneNumber is null
number = Convert.ToInt64(phoneNumber);
// does not throw, but returns true on success
if (Int64.TryParse(phoneNumber, NumberStyles.Integer,
CultureInfo.InvariantCulture, out number))
{
// parse was successful
}

Since nobody did a for loop.
long GetPhoneNumber(string PhoneNumberText)
{
// Returns 0 on error
StringBuilder TempPhoneNumber = new StringBuilder(PhoneNumberText.Length);
for (int i=0;i<PhoneNumberText.Length;i++)
{
if (!char.IsDigit(PhoneNumberText[i]))
continue;
TempPhoneNumber.Append(PhoneNumberText[i]);
}
PhoneNumberText = TempPhoneNumber.ToString();
if (PhoneNumberText.Length == 0)
return 0;// No point trying to parse nothing
long PhoneNumber = 0;
if(!long.TryParse(PhoneNumberText,out PhoneNumber))
return 0; // Failed to parse string
return PhoneNumber;
}
used like this:
long phoneNumber = GetPhoneNumber("(123) 456-7890");
Update
As pr commented many countries do have zero's in the begining of the number, if you need to support that, then you have to return a string not a long. To change my code to do that do the following:
1) Change function return type from long to string.
2) Make the function return null instead of 0 on error
3) On successfull parse make it return PhoneNumberText

You can make it work for that number with the addition of a simple regex replacement, but I'd look out for higher initial digits. For example, (876) 543-2019 will overflow an integer variable.

string digits = Regex.Replace(formatted, #"\D", String.Empty, RegexOptions.Compiled);

Aside from all of the other correct answers, storing phone numbers as integers or otherwise stripping out formatting might be a bad idea.
Here are a couple considerations:
Users may provide international phone numbers that don't fit your expectations. See these examples So the usual groupings for standard US numbers wouldn't fit.
Users may NEED to provide an extension, eg (555) 555-5555 ext#343 The # key is actually on the dialer/phone, but can't be encoded in an integer. Users may also need to supply the * key.
Some devices allow you to insert pauses (usually with the character P), which may be necessary for extensions or menu systems, or dialing into certain phone systems (eg, overseas). These also can't be encoded as integers.
[EDIT]
It might be a good idea to store both an integer version and a string version in the database. Also, when storing strings, you could reduce all punctuation to whitespace using one of the methods noted above. A regular expression for this might be:
// (222) 222-2222 ext# 333 -> 222 222 2222 # 333
phoneString = Regex.Replace(phoneString, #"[^\d#*P]", " ");
// (222) 222-2222 ext# 333 -> 2222222222333 (information lost)
phoneNumber = Regex.Replace(phoneString, #"[^\d]", "");
// you could try to avoid losing "ext" strings as in (222) 222-2222 ext.333 thus:
phoneString = Regex.Replace(phoneString, #"ex\w+", "#");
phoneString = Regex.Replace(phoneString, #"[^\d#*P]", " ");

Try this:
string s = "(123) 456-7890";
UInt64 i = UInt64.Parse(
s.Replace("(","")
.Replace(")","")
.Replace(" ","")
.Replace("-",""));
You should be safe with this since the input is masked.

You could use a regular expression or you could loop over each character and use char.IsNumber function.

You would be better off using regular expressions. An int by definition is just a number, but you desire the formatting characters to make it a phone number, which is a string.
There are numerous posts about phone number validation, see A comprehensive regex for phone number validation for starters.

As many answers already mention, you need to strip out the non-digit characters first before trying to parse the number. You can do this using a regular expression.
Regex.Replace("(123) 456-7890", #"\D", String.Empty) // "1234567890"
However, note that the largest positive value int can hold is 2,147,483,647 so any number with an area code greater than 214 would cause an overflow. You're better off using long in this situation.
Leading zeros won't be a problem for North American numbers, as area codes cannot start with a zero or a one.

Alternative using Linq:
string phoneNumber = "(403) 259-7898";
var phoneStr = new string(phoneNumber.Where(i=> i >= 48 && i <= 57).ToArray());

This is basically a special case of C#: Removing common invalid characters from a string: improve this algorithm. Where your formatng incl. White space are treated as "bad characters"

'you can use module / inside sub main form VB.net
Public Function ClearFormat(ByVal Strinput As String) As String
Dim hasil As String
Dim Hrf As Char
For i = 0 To Strinput.Length - 1
Hrf = Strinput.Substring(i, 1)
If IsNumeric(Hrf) Then
hasil &= Hrf
End If
Next
Return Strinput
End Function
'you can call this function like this
' Phone= ClearFormat(Phone)

public static string DigitsOnly(this string phoneNumber)
{
return new string(
new[]
{
// phoneNumber[0], (
phoneNumber[1], // 6
phoneNumber[2], // 1
phoneNumber[3], // 7
// phoneNumber[4], )
// phoneNumber[5],
phoneNumber[6], // 8
phoneNumber[7], // 6
phoneNumber[8], // 7
// phoneNumber[9], -
phoneNumber[10], // 5
phoneNumber[11], // 3
phoneNumber[12], // 0
phoneNumber[13] // 9
});
}