Substrings: part of a string by position (usually starting at 0): "Computer".SUBSTRING(0,3) = "Com".
Case: UPPER and LOWER convert the case.
Position/indexing: the first character is at index 0.
Searching: finding where a character or word appears; checking if a string contains a substring.
ASCII conversion: ASC("A") = 65 and CHR(65) = "A".
String length and case
Comparing strings
For the simple ASCII examples here, comparison is case-sensitive and follows character codes: apple comes before banana and A differs from a.
Language-specific collation and Unicode processing can differ; state comparison and normalisation rules when needed.
Common tasks
Reverse a non-empty string by visiting indices LEN(s) − 1 down to 0 and appending each character to an initially empty result.
A palindrome equals its reverse under the chosen comparison rules. Check for an empty string before accessing s[0]; counting vowels can use traversal and selection.
Casting and conversion
Convert numbers to strings and back when joining or calculating.
ASCII conversion
ASC gives a character code
CHR gives the character
ASC("A") = 65
Characters and ASCII codes
幻灯片
Sign up free to view the lesson slides
Step through every slide for this topic — plus flashcards and revision notes — with a free account.
