Is there a method in C# to check if a string is a valid identifier [duplicate]

Answer 1

The now-released Roslyn project provides Microsoft.CodeAnalysis.CSharp.SyntaxFacts, with SyntaxFacts.IsIdentifierStartCharacter(char) and SyntaxFacts.IsIdentifierPartCharacter(char) methods just like Java.

Here it is in use, in a simple function I use to turn noun phrases (eg "Start Date") into C# identifiers (eg "StartDate"). N.B I'm using Humanizer to do the camel-case conversion, and Roslyn to check whether a character is valid.

    public static string Identifier(string name)
    {
        Check.IsNotNullOrWhitespace(name, nameof(name));

        // trim off leading and trailing whitespace
        name = name.Trim();

        // should deal with spaces => camel casing;
        name = name.Dehumanize();

        var sb = new StringBuilder();
        if (!SyntaxFacts.IsIdentifierStartCharacter(name[0]))
        {
            // the first characters 
            sb.Append("_");
        }

        foreach(var ch in name)
        {
            if (SyntaxFacts.IsIdentifierPartCharacter(ch))
            {
                sb.Append(ch);
            }
        }

        var result = sb.ToString();

        if (SyntaxFacts.GetKeywordKind(result) != SyntaxKind.None)
        {
            result = @"@" + result;
        }

        return result;
    }

Tests;

    [TestCase("Start Date", "StartDate")]
    [TestCase("Bad*chars", "BadChars")]
    [TestCase("   leading ws", "LeadingWs")]
    [TestCase("trailing ws   ", "TrailingWs")]
    [TestCase("class", "Class")]
    [TestCase("int", "Int")]
    [Test]
    public void CSharp_GeneratesDecentIdentifiers(string input, string expected)
    {
        Assert.AreEqual(expected, CSharp.Identifier(input));
    }