C#
String helpers
Add and test string processing methods.
String helpers
Our first helper method is Capitalize: it uppercases only the first letter of a string. Declaration: public static string Capitalize(string text). Being static, it is called directly as Helpers.Capitalize("hello").
In the body we first check for empty with string.IsNullOrEmpty(text); then we uppercase the first letter with char.ToUpper(text[0]) and append the rest with text.Substring(1). Result: "Hello". This is useful to clean up names entered by users.
Using Capitalize
Once you write a helper method, you can call it from anywhere. Example: string name = Helpers.Capitalize("alex");. This puts user input into a consistent form.
This is why helper libraries are valuable: write once, use a thousand times. Instead of copying the same code, you call Helpers.Capitalize. If you find a bug, you fix it in one place; all callers update automatically.
Exercise Add the Capitalize method and call it
The Helpers class below is empty. Add a public static string Capitalize(string text) method to it. In the body check for empty with if (string.IsNullOrEmpty(text)) return text;, then write return char.ToUpper(text[0]) + text.Substring(1);. Inside Main print Helpers.Capitalize("hello").
Show example solution
Add the Capitalize method to Helpers. In Main write Console.WriteLine(Helpers.Capitalize("hello"));
Example solution:
using System;
static class Helpers
{
public static string Capitalize(string text)
{
if (string.IsNullOrEmpty(text)) return text;
return char.ToUpper(text[0]) + text.Substring(1);
}
}
class Program
{
static void Main()
{
Console.WriteLine("Ready");
Console.WriteLine(Helpers.Capitalize("hello"));
}
}
Test yourself
-
What does Capitalize return?
Helpers.Capitalize("hello")
Show answer
"Hello" — Correct. Only the first letter is uppercased: "Hello".
-
Complete the Capitalize body
return char.ToUpper(text[0]) + text.____(1);
Show answer
return char.ToUpper(text[0]) + text.Substring(1);
-
Match each method to its behavior
- Capitalize
- Uppercases first letter
- ToUpper
- Uppercases a letter
- Substring
- Takes a portion
- IsNullOrEmpty
- Checks if empty
Next lesson: Number helpers
