C# IsBetween String Logic - c#-4.0

Question

Looking for either a solution, some ideas or being point in the right direction on how to resolve a problem.
Basically, I have to figure out if a string value is in between a Low and High string value. However, the values are in a format which String.Compare will not work. But, a human can easily figure out.
For example, one of my ranges is Low: A7, High A12. A8 fits in between those values but String.Compare says it does not. A13 would not fit between the values.
Other examples of Low and High values are:
Low Value - High Value
1A1 - 1A12
25W00 - 25W050
42W1 - 42W296
W232N0002 - W232N000598
In the above examples 1A2 would fit between the Low High Value of 1A1 and 1A12, but 1A100 would not.
Any ideas on how to resolve this? I know this had to have been encountered before.

Answer 1

This could use some optimization, but it's a proof of concept.
Just convert the letters to numerical values and compare the results:
private bool ValueIsBetween(string value, string lowValue, string highValue)
{
long low = long.Parse(ConvertToNumber(lowValue));
long high = long.Parse(ConvertToNumber(highValue));
long val = long.Parse(ConvertToNumber(value));
return val > low && val < high;
}
private string ConvertToNumber(string value)
{
value = value.ToUpper();
value = value.Replace("A", "0");
value = value.Replace("B", "1");
value = value.Replace("C", "2");
value = value.Replace("D", "3");
value = value.Replace("E", "4");
value = value.Replace("F", "5");
value = value.Replace("G", "6");
value = value.Replace("H", "7");
value = value.Replace("I", "8");
value = value.Replace("J", "9");
value = value.Replace("K", "10");
value = value.Replace("L", "11");
value = value.Replace("M", "12");
value = value.Replace("N", "13");
value = value.Replace("O", "14");
value = value.Replace("P", "15");
value = value.Replace("Q", "16");
value = value.Replace("R", "17");
value = value.Replace("S", "18");
value = value.Replace("T", "19");
value = value.Replace("U", "20");
value = value.Replace("V", "21");
value = value.Replace("W", "22");
value = value.Replace("X", "23");
value = value.Replace("Y", "24");
value = value.Replace("Z", "25");
return value;
}
Results:
ValueIsBetween("1A2", "1A1", "1A12");
true
ValueIsBetween("1A100", "1A1", "1A12");
false
ValueIsBetween("43W4", "42W1", "44W3");
true
Edit:
Try this improved algorithm instead:
private bool ValueIsBetween(string value, string lowValue, string highValue)
{
return !ValueIsLessThan(value, lowValue) && ValueIsLessThan(value, highValue);
}
private bool ValueIsLessThan(string value, string compareTo)
{
var matches = Regex.Matches(value, "[0-9]+|[a-zA-Z]+");
var matchesB = Regex.Matches(compareTo, "[0-9]+|[a-zA-Z]+");
var count = matches.Count < matchesB.Count ? matches.Count : matchesB.Count;
for (int i = 0; i < count; i++)
{
long val;
long val2;
if (long.TryParse(matches[i].Value, out val))
{
if (long.TryParse(matchesB[i].Value, out val2))
{
if (val > val2) return false;
if (val < val2) return true;
}
else
{
return false;
}
}
else
{
if (matches[i].Value.CompareTo(matchesB[i].Value) > 0 ) return false;
if (matches[i].Value.CompareTo(matchesB[i].Value) < 0 ) return true;
}
}
return true;
}
Results:
ValueIsBetween("B431Z543", "A0", "Z9");
true
ValueIsBetween("4B31Z543", "A0", "Z9");
false
ValueIsBetween("1A2", "1A1", "1A12");
true
ValueIsBetween("1A100", "1A1", "1A12");
false
ValueIsBetween("43W4", "42W1", "44W3");
true
ValueIsBetween("W5", "CC4", "CC6");
false
ValueIsBetween("W8B4", "W5C3", "W7C3");
false
ValueIsBetween("W5C4", "W5C3", "C7W3");
false

Answer 2

Build a class, probably abstract, with sub classes for each pattern.
The pattern for "25W00" could be ^(?<LEFTTHING>.{2})(?<MIDDLETHING>.{1})(?<RIGHTTHING>.{2})$
In your class, capture each Regex group as a string or numeric as appropriate.
I suppose you could come up with some conventions so you might even be able to have a single Type - and pass in that pattern to the constructor.
You may even have some kind of really smart class where you pass in two strings and a common pattern. This super class builds appropriate "comparable" classes (as per above) and returns a boolean result of the comparison. Your client code would be very clean in this case.

Answer 3

Assuming the non-numeric parts are fixed (i.e. you aren't searching for 1B1 being between 1A1 and 1C1), you could use a regex to expand the numerical values to a certain fixed width, so you could then compare the strings.
For example, using
static Regex digits = new Regex(#"\d+");
static string ExpandDigits(string s)
{
return digits.Replace(s, m => string.Format("{0:D10}", int.Parse(m.ToString())));
}
then calling ExpandDigits("W232N0002") yields W0000000232N0000000002.
You could have a comparison method like this:
static bool IsInRange(string lower, string upper, string test)
{
test = ExpandDigits(test);
lower = ExpandDigits(lower);
if (lower.CompareTo(test) <= 0)
{
upper = ExpandDigits(upper);
if (test.CompareTo(upper) <= 0)
{
return true;
}
}
return false;
}