How do I make my string compare not sensitive to (ignore) minor differences in white space?

Question

I have some tests that check strings that are displayed to the user.

I don’t wish the test to fail to due to changes in the indentations or line breaks etc. So I am looking for something like a string compare that.

• Ignore while space as the start of the string (easy use string.trim)
• When any number of any type of white space that is next to each other matches in the same way as if it was a single space.

I could start to create a regex, but someone else may have a better solution hence this question.

Answer 1

You can use CompareOptions:

String.Compare(a, b, CultureInfo.CurrentCulture, CompareOptions.IgnoreSymbols);

Extract from MSDN:

Indicates that the string comparison must ignore symbols, such as white-space characters, punctuation, currency symbols, the percent sign, mathematical symbols, the ampersand, and so on.

Answer 2

Writing a custom compare would be tricky if you need it just to do this for whitespace. I would suggest using regex to normalize, i.e.

private static readonly Regex normalizeSpace =
        new Regex(@"\s+", RegexOptions.Compiled);
...
string s = normalizeSpace.Replace(input, " ");

Obviously normalize both operands and then test for equality as normal.

Answer 3

You can also use the following custom function

        public static string ExceptChars(this string str, IEnumerable<char> toExclude)
        {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < str.Length; i++)
            {
                char c = str[i];
                if (!toExclude.Contains(c))
                    sb.Append(c);
            }
            return sb.ToString();
        }

        public static bool SpaceInsenstiveComparision(this string stringa, string stringb)
        {
            return stringa.ExceptChars(new[] { ' ', '\t', '\n', '\r' }).Equals(stringb.ExceptChars(new[] { ' ', '\t', '\n', '\r' }));
        }

And then use it following way

"Te  st".SpaceInsenstiveComparision("Te st");