string.EndsWith()

Question

I need to check in string.Endswith("") from any of the following operators: "+,-,*,/"

If I have 20 operators I don't want to use "||" operator 19 times.

Answer 1

Is a regex expression not an option

Answer 2

Although a simple example like that is probably good enough using ||, you can also use Regex for it:

if (Regex.IsMatch(mystring, @"[-+*/]$")) {
  ...
}

Answer 3

If you really want to, you can use De Morgan's laws to replace x || y in your code. One version says:

!(x || y) == !x && !y

If you want to have the same result, we just need to negate the entire expression twice:

x || y == !!(x || y) == !(!x && !y)

Answer 4

If you are using .NET 3.5 then it is quite easy with LINQ:

string test = "foo+";
string[] operators = { "+", "-", "*", "/" };
bool result = operators.Any(x => test.EndsWith(x));

Answer 5

Test the last char of the string using String.IndexOfAny(Char[], Int32) method (assuming str is your variable):

str.IndexOfAny(new char[] {'+', '-', '*', '/'}, str.Length - 1)

Complete expression:

str.Lenght > 0 ? str.IndexOfAny(new char[] {'+', '-', '*', '/'}, str.Length - 1) != -1 : false

Answer 6

Given the complete lack of context, would this solution that is worse than using an easy || operator be of use:

Boolean check = false;
if (myString.EndsWith("+"))
     check = true;

if (!check && myString.EndsWith("-"))
     check = true;

if (!check && myString.EndsWith("/"))
     check = true;

etc.

Answer 7

string s = "Hello World +";
string endChars = "+-*/";

Using a function:

private bool EndsWithAny(string s, params char[] chars)
{
    foreach (char c in chars)
    {
        if (s.EndsWith(c.ToString()))
            return true;
    }
    return false;
}

bool endsWithAny = EndsWithAny(s, endChars.ToCharArray()); //use an array
bool endsWithAny = EndsWithAny(s, '*', '/', '+', '-');     //or this syntax

Using LINQ:

bool endsWithAny = endChars.Contains(s.Last());

Using TrimEnd:

bool endsWithAny = s.TrimEnd(endChars.ToCharArray()).Length < s.Length;
// als possible s.TrimEnd(endChars.ToCharArray()) != s;

Answer 8

How about:-

string input = .....;
string[] matches = { ...... whatever ...... };

foreach (string match in matches)
{
    if (input.EndsWith(match))
        return true;
}

I know it is dreadfully old school to avoid LINQ in this context, but one day you will need to read this code. I am absolutely sure that LINQ has its uses (maybe i'll find them one day) but i am quite sure it is not meant to replace the four lines of code above.

Answer 9

Using String.IndexOf(String):

str.Lenght > 0 ? "+-*/".IndexOf(str[str.Lenght - 1]) != -1 : false