检查文本框中是否有任何字符

Question

I have a chararray on global, button and textbox, how do I check if the word in textBox1.Text contains the letters in the chararray?

char[] letters = { 'a', 'e' };

private void button1_Click(object sender, EventArgs e)
{
    bool containsAnyLetter = textBox1.Text.IndexOfAny(letters) >= 0;

    if (containsAnyLetter == true)
    {
        MessageBox.Show("your word contains a or e");
    }
}

Answer 1

You can do this to see if the string contains any of the letters:

private void button1_Click(object sender, EventArgs e)
{
    bool containsAnyLetter = letters.Any(c => textBox1.Text.Contains(c));
}

Or more simply:

private void button1_Click(object sender, EventArgs e)
{
    bool containsAnyLetter = textBox1.Text.IndexOfAny(letters) >= 0;
}

Answer 2

You can use the String.IndexOfAny(char[] anyOf) method ( MSDN ):

private void button1_Click(object sender, EventArgs e)
{
    if (textBox1.Text.IndexOfAny(letters) >= 0)
    {
        MessageBox.Show("Your word contains a or e.");
    }
}

Also, keep in mind that IndexOfAny is case-sensitive ( a will not match A ).

If you want to create a case-insensitive method, you could create an extension method:

public static class StringIndexExtensions
{
    public static bool CaseSensitiveContainsAny(this char[] matchChars, string textToCheck)
    {
        return matchChars.Any(c => textToCheck.IndexOf(
            c.ToString(CultureInfo.InvariantCulture),
            StringComparison.OrdinalIgnoreCase) >= 0);
    }
}

Then you could do the following:

private void button1_Click(object sender, EventArgs e)
{
    if (letters.CaseSensitiveContainsAny(textBox1.Text))
    {
        MessageBox.Show("Your word contains a or e.");
    }
}

Answer 3

You can use Regex

private void button1_Click(object sender, EventArgs e)
        {
            if (Regex.IsMatch(textBox1.Text, @"(a|e)"))
            {
                MessageBox.Show("your word contains a or e");
            }
        }