C# code:

static void Main(string[] args)
{
    string param = "I devour kittens";

    Console.WriteLine(ReverseWords(param));
    Console.ReadLine();
}

// assume internal input
public static string ReverseWords(string input)
{
    input = Reverse(input);

    string[] inputWords = input.Split(' ');
    for (int i = 0; i < inputWords.Length; i++)
    {
        inputWords[i] = Reverse(inputWords[i]);
    }

    return string.Join("", inputWords);
}

public static string Reverse(string input)
{
    char[] inputCharArray = new char[input.ToCharArray().Length];
    for (int i = 0; i < input.ToCharArray().Length; i++)
    {
        inputCharArray[i] = input[inputCharArray.Length - (i + 1)];
    }
    return string.Join("", inputCharArray);
}