Concept Exercise for Strings

[pwadsworth]

Develop concept exercise(s) to practice the Strings concept covering the following topics:

1. Insert unicode characters in strings
2. Verify Char properties (isAlpha, isUpper...)
3. Use basic string functions (length, replace...)
4. Split and join strings (split, words, lines, (++), concat, join...)
5. Cut up strings (slice, left...)
6. Check for substrings (contains, startsWith...)
7. Convert to and from other types (fromInt, toInt...)
8. Format a string (toUpper, toLower, trim...)
9. Use some higher order functions (all, any, filter...)

Recommendations:

• 99-Beers: Covers 1, 3, 4 (partial), and 7 above.
• Squeaky Clean: Covers 1, 2, 3, 4, 5, 6, and 8 above

[jiegillet]

There is one last thing we should do on this issue before closing: go through existing practice exercises and add the "strings" concept to the relevant ones ("prerequisites" field for concept exercises and "prerequisites"/"practices" for practice exercises).
We already have the (obsolete) "topics" on the exercises, which sometimes contains "strings". That should help.

[pwadsworth]

There is one last thing we should do on this issue before closing: go through existing practice exercises and add the "strings" concept to the relevant ones ("prerequisites" field for concept exercises and "prerequisites"/"practices" for practice exercises). We already have the (obsolete) "topics" on the exercises, which sometimes contains "strings". That should help.

I'll tackle this over the next week.

[jiegillet]

Closed via #629