Appendix B: Keyword Glossary

Every reserved word in QF Code 1.1.0, in plain language, with a pointer to the chapter where it's actually taught. All keywords are case-insensitive; this book writes them lowercase throughout. Reserved words can't be used as variable, constant, or function names.

Declarations

var: Declares a variable, a named place to store a value that can change later. Chapter 2.

const: Declares a constant, a named value that can never be reassigned once set. Requires a value up front. Chapters 2 and 11.

Conditionals

if / then / else if / else / end if: Runs a block of code only when a condition is true, with optional alternatives. end if closes the block. Chapter 3.

Loops

while / end while: Repeats a block for as long as a condition stays true, checked before every pass. Chapter 4.

for / to / step / end for: Repeats a block a specific, counted number of times. step optionally sets how much the counter changes each pass; without it, the step is 1 (or -1 if counting downward). Chapter 4.

for each / in / end for: Steps through every item in an array or string, one at a time, without managing a counter yourself. Chapters 4 and 5.

break: Exits the current loop immediately, regardless of its condition. Chapter 4.

continue: Skips the rest of the current pass through a loop and jumps to the next condition check. Chapter 4.

Branching on a Value

match / when / when else / end match: Compares one value against several possibilities, running only the first branch that matches. when else is an optional catch-all. Chapter 9.

to (inside match): Marks an inclusive range in a when clause, such as when 80 to 89. Chapter 9.

Functions

function / return / end function: Declares a named, reusable block of code. return sends a value back to whoever called it; a function that never reaches return sends back empty automatically. Chapter 6.

Error Handling

attempt / error / end attempt: Runs a block of code that might fail, and catches the failure instead of letting it crash the whole program. Naming a variable after error captures the error message. Chapter 10.

signal: Raises a runtime error on purpose, with a message you choose, the same kind of error an attempt block can catch. Chapter 10.

Literals

true / false: The two boolean values. Chapter 2.

empty: Represents the absence of a value, QF Code's equivalent of "nothing here." A function with no return sends back empty automatically. Chapters 2 and 6.

Logical Operators

and: Combines two conditions; true only when both sides are true. Short-circuits, skipping the right side if the left side is already false. Chapter 3.

or: Combines two conditions; true when either side is true. Short-circuits, skipping the right side if the left side is already true. Chapter 3.

xor: True when exactly one of two conditions is true, not both and not neither. Always checks both sides. Chapter 3.

not: Reverses a boolean value: true becomes false and vice versa. Chapter 3.

---