using System;
using System.Text.RegularExpressions;
public class Test
{
public static void Main()
{
string pattern = @"(?!^[ ]{0,}$)^\S{1,}$";
string input = @"
abcd
ABCD1234
#$%^&*()_+={}
abc def
ABC 123
";
RegexOptions options = RegexOptions.Multiline;
foreach (Match m in Regex.Matches(input, pattern, options))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
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