Round #733

Concatenate two strings and trim whitespace.

```csharp using System; class Program { static void Main() { // Define the two strings string str1 = "Hello, "; string str2 = "World! "; // Concatenate the strings and strip whitespace string result = (str1 + str2).Trim(); Console.WriteLine(result); // Output: "Hello, World!" } } ```

```csharp using System; public class StringConcatenator { public static string ConcatAndTrim(string str1, string str2) { if (str1 == null || str2 == null) { throw new ArgumentNullException("Both input strings must be non-null."); } string concatenated = str1 + str2; return concatenated.Trim(); } public static void Main() { string str1 = "Hello, "; string str2 = " World! "; string result = ConcatAndTrim(str1, str2); Console.WriteLine(result); // Outputs: "Hello, World!" } } ``` This C# code defines a method `ConcatAndTrim` that concatenates two input strings and trims any leading or trailing whitespace from the result. The `Main` method demonstrates how to use this function with example strings. The code includes error handling to ensure that both input strings are non-null.