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using System.Linq;
public static class Bob
{
private static readonly string[] answers = {"Whatever.", "Sure.", "Whoa, chill out!", "Calm down, I know what I'm doing!"};
public static string Response(string statement)
{
var input = statement.TrimEnd();
if (input == "")
return "Fine. Be that way!";
var isShout = input.Any(c => char.IsLetter(c)) && input.ToUpper() == input ? 2: 0;
var isQuestion = input.EndsWith('?') ? 1: 0;
return answers[isShout + isQuestion];
}
}
In this approach you define an array that contains Bob’s answers, and each condition is given a score. The correct answer is selected from the array by using the score as the array index.
The String TrimEnd method is applied to the input to eliminate any whitespace at the end of the input.
If the string has no characters left, it returns the response for saying nothing.
Note that a null string would be different from a string of all whitespace.
A null string would throw an Exception if TrimEnd were applied to it.
To test a string that might be null or only whitespace, the IsNullOrWhiteSpace method of String would be used.
The first half of the shout condition
input.Any(c => char.IsLetter(c)) && input.ToUpper() == input
is constructed from the Any LINQ method and the IsLetter Char method to ensure there is at least one letter character in the String.
This is because the second half of the condition tests that the uppercased input is the same as the input.
If the input were only "123" it would equal itself uppercased, but without letters it would not be a shout.
The conditions of being a question and being a shout are assigned scores through the use of the ternary operator.
For example, giving a question a score of 1 would use an index of 1 to get the element from the answers array, which is "Sure.".
| isShout | isQuestion | Index | Answer |
|---|---|---|---|
false |
false |
0 + 0 = 0 | "Whatever." |
false |
true |
0 + 1 = 1 | "Sure." |
true |
false |
2 + 0 = 2 | "Whoa, chill out!" |
true |
true |
2 + 1 = 3 | "Calm down, I know what I'm doing!" |
Shortening
When the body of an if statement is a single line, both the test expression and the body could be put on the same line, like so
if (input == "") return "Fine. Be that way!";
The C# Coding Conventions advise to write only one statement per line in the layout conventions section, but the conventions begin by saying you can use them or adapt them to your needs. Your team may choose to overrule them.
For Any, the lambda expression of c => char.IsLetter(c) can be shortened to just the method call of char.IsLetter like so
input.Any(char.IsLetter)
Any passes a single character in each iteration, and the char.IsLetter method is called on that character implicitly.
There is a detailed description of how it works in the accepted answer for this StackOverflow question.
