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Compare several strings in an if statement [closed]

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Is there a better way to do this?
var line = sr.ReadLine();
string[] values = line.Split(';');
if (d == "abc"|| d == "def"|| d == "ghi")
{
}
Since I seemed to get an error message regarding this if statement I added && false to every comparison and replaced the == with the equals method, both without positive results, but this turned out irrelevant.

I can recommend this
notice that if d is null no exception is throw
And also you can extend your list for other compare strings if necessary
You do not need to write a large if statement with comparing d for each string
string d = values[10];
var list = new List<string>() { "abc", "def", "ghi" };
if (!list.Contains(d))
{
}

C# Sorting string list with underscore and hyphen [closed]

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I have a List<string> with values SK-Disbur and SK_Recon. When I sort the list, what should be the output?
I am getting:
SK_Recon
SK-Disbur
I was expecting the other way around with Disbur before Recon, since hyphen comes before underscore.
Here is my code:
List<string> list=new List<string>();
list.Add("SK-Disbur");
list.Add("SK_Recon");
list.Sort();
for(int i=0;i <list.Count;i ++)
{
Console.WriteLine(list[i]);
}

.NET doesn't use ASCII, it uses Unicode UTF-16. When you perform a string sort, By default .NET are using the current culture's rules for sorting. In this case, those rules indicate that "_" comes before "-". You can get the result you expect by using the "ordinal" string comparer:
List<string> list = new List<string>()
{
"SK-Disbur",
"SK_Recon",
"SK1",
"SK2"
};
list.Sort(StringComparer.Ordinal);
for (int i = 0; i < list.Count; i++)
{
Console.WriteLine(list[i]);
}
you will get this result
SK-Disbur
SK1
SK2
SK_Recon
but if you use list.Sort() (by default) the result is very different
SK_Recon
SK-Disbur
SK1
SK2

By default list.Sort() uses the current culture's rules for sorting. That means each character is sorted using a linguistic sort (alphabetic sequence). You should use ordinal sorting so that its sorted by the binary value of each character. Try:
list.Sort(StringComparer.Ordinal);

How to convert 2 properties of every record in a List from string to int(by extracting numbers from string) C# [closed]

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Currently, I have a List of objects. Each record has three properties.
HEID = string type,(The string always looks like 12R,27L,36)
LEID = string type,(The string always looks like 12R,27L,36)(I want to
extract the numbers and set them as an int.)
RunwayId = int,
I want to take the HEId and LEId strings, and extract the numbers, and store it as a new List, or change the current properties to int type with converted values.
I am looping through the list, and this is where I want to convert each record's string type property to int type.
Thanks

yourList.Select(obj => new { HEID = float.Parse(obj.HEID), LEID = float.Parse(obj.LEID) });
this will return an IEnuramble of anonymous objects
you can also create new type with these properties as int and instead of selecting an anonymous type u can cast or select to the new type
yourList.Select(obj => new NewTypeWithInt { HEID = float.Parse(obj.HEID), LEID = float.Parse(obj.LEID) });
or even cleaner you can create a cast opreator
yourList.Select(obj => (NewTypeWithInt)obj);

Put a string into a linq expression? [closed]

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I need to do a LINQ expression where the expression varies on how deep the expected node is in the hierarchy.
So I use concat on a string like this:
var parString = string.Concat(Enumerable.Repeat(".SelectMany(f => f.level)", level));
so if its 4 levels deep I get the string :
string1 = ".SelectMany(f => f.level).SelectMany(f => f.level).SelectMany(f => f.level).SelectMany(f => f.level)"
I then want to use this string in a LINQ expression, example:
List + string1 + .FirstOrDefault(.......);
Is this even possible? How can I do it?

Use a for loop to determine how many times to call .SelectMany:
var query = List;
for(int depth = 4; depth > 0; depth--)
{
query = query.SelectMany(f => f.level);
}
// Materialize query with `FirstOrDefault` or anything you need
Notice that currently if you reach the maximum depth and still continue you will get an exception. To solve that you can add an if statement to check that f.level is not null or not empty depending on your logic. Something like:
for(int depth = 4; depth > 0; depth--)
{
query = query.SelectMany(f => f.level ?? Enumerable.Empty<YourType>());
}

richtextbox application test c# [closed]

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I'm very new to c#. I created a forms. A richtextbox and a button in it.
I have a list of operators: Sum, Subtract,Multi,Div.I want to run a small richtextbox test. For example,in the richtextbox I write a text (eg. Sum(1,2)) and then click the button. A return result(eg.3) prints in the richtextbox.
My idea is to use string contains
foreach( var element in operatorlist)
{
string text=richtextbox.text;
if( text.contains(element)== true)
{
element(parameter1,parameter2);//something like this
}
}
I met two questions right row.
My first question is how to get the mathematical operation from the richtextbox text. Is there a better way than mine?
My second question is once we know the operator,how to allocate the two parameters in the richtextbox to the operator.
I'm not asking for coding, I'm just looking for ideas. If you have a good idea and wish to share.

You can evaluate an expression using the DataTable.Compute function:
int p1 = 1 ; string s1 = p1.ToString() ;
int p2 = 2 ; string s2 = p2.ToString() ;
int p3 = 3 ; string s3 = p3.ToString() ;
// Compute (p1+p2)*p3 ==> 9
int result = new DataTable().Compute( "("+s1+"+"+s2+")*"+s3+")","") ;
or directly:
string expression = "(1+2)*3" ;
int result = new DataTable().Compute(expression,"") ;

I think this comes down to personal style. Your way will definitely work, so good on you for that. The way I would do it is to create a Dictionary of strings to an enum. So for example, said dictionary and enum might look like this:
enum Operator { Addition = 0, Subtraction = 1, Multiplication = 2, Division = 3, etc};
var operatorDictionary = new Dictionary<string, Operator>()
{
{"Addition", Operator.Addition},
{"Subtraction", Operator.Subtraction},
etc...
};
Then to get the value you would just do
Operator operation;
operatorDictionary.TryGetValue(string operationString, out operation);
and you would have to then build some code that switches through the Operators and performs the correct operation. There is even a way of converting a string to an enum, so that would work as well.
It looks like the parameters are in a consistent format, so you would just make a simple method that splits by parenthesis and the comma, and returns the strings that it found.
Let me know if you need anything explained more.