Turn a product title into a URL slug
The catalogue builds a URL from each product title, and the result has to be safe to put in a path.
- Lowercase, and keep only letters a-z and digits.
- Every run of anything else collapses to a single dash.
- No dash at the start or the end.
- A title with nothing usable in it gives an empty string.
Slugify(title: string) → string
C# needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
public string Slugify(string title) {
}Worked examples
| Call | Result |
|---|---|
Slugify(" Blue Widget, 12mm! ") | "blue-widget-12mm" |
Slugify("A---B") | "a-b" |
Slugify("Already-slugged") | "already-slugged" |
Slugify("!!!") | "" |
Hint
Append a dash only when there is already something to separate, then trim the one you may have left on the end.
Reference solution in C#
public string Slugify(string title) {
var sb = new StringBuilder();
foreach (char ch in title.ToLowerInvariant()) {
if ((ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9')) sb.Append(ch);
else if (sb.Length > 0 && sb[sb.Length - 1] != '-') sb.Append('-');
}
if (sb.Length > 0 && sb[sb.Length - 1] == '-') sb.Length--;
return sb.ToString();
}