String Handling Operations In A Programming

A program is handed the text AB-2481 and has to work out that the last four characters are a number, that the hyphen is in the right place, and that the whole thing is seven characters long. None of that is arithmetic and none of it is guesswork. Each step is one of a small set of operations on text, and this specification names seven of them.

This lesson covers all seven: finding the length of a string, finding the position of something inside it, taking a substring out of it, joining strings by concatenation, converting a character to its character code and back again, and the string conversion operations that turn text into numbers and numbers into text. Together they are how a program reads a reference code, splits a name into initials, validates a password and turns keyboard input into something it can add up.