Appendix A: Complete Built-in Reference (QF Code 1.1.0)

Every built-in function in QF Code 1.1.0, organized by purpose. Each entry has been traced against the actual 1.1.0 shell behavior, not written from the language specification alone. Written lowercase throughout, matching this book's style; QF Code itself is case-insensitive.

Output and Input

write(value, ...): Prints one or more values, space-joined, without starting a new line. A later write() or writeln() continues on the same line. Chapter 1.

write("A")
write("B")   // still on the same line as "A"

writeln(value, ...): Prints one or more values, space-joined, and always completes its own line, even if a write() left a line open. Chapter 1.

writeln("Hello, adventurer.")

input(prompt): Requires a string prompt. Pauses the program until the player types something and presses Enter. Always returns a string, even if the player types a number. Chapter 2.

var name = input("What is your name? ")

Program Control

erase(): With no argument, clears the output panel. Chapter 1 (mentioned), used directly if you want to clear the screen.

erase(array): Removes every item from the given array, in place. Chapter 5.

stop(): Intended to halt the whole program immediately. Worth knowing as of 1.1.0: a standalone stop() line at the top level or inside a function doesn't currently behave as cleanly as calling it from inside an expression does. If you need reliable early termination, a return from a function or a loop's break is the more dependable tool for now.

signal(message): Raises a runtime error with the message you give it, the kind of error an attempt block can catch. Chapter 10.

Sound

sound(pitch, duration_ms): Plays a tone. pitch can be a frequency in hertz, or a note name like "C4", "A#3", or "Bb5". Blocks the program until the tone finishes. Chapter 12.

sound("C4", 150)

bell(): Plays a short, fixed tone (880 Hz for 150 ms), no arguments. Also blocks until it finishes. Chapter 12.

Type Conversion

str(value): Converts any value to its display text form, the same form writeln() would print. Chapter 2.

str(true)     // "TRUE"
str(empty)    // "EMPTY"

num(value): Converts a value to a number. Numbers pass through unchanged, true/false become 1/0, and strings are converted the same way JavaScript's Number() would. A string that can't become a valid number raises an error. Chapter 2.

num("4")      // 4
num("")       // 0

bool(value): Converts certain values to a boolean. Accepts true, 1, "true", and "TRUE" as true; false, 0, "false", "FALSE", and empty as false. Anything else raises an error, and mixed-case strings like "True" are not accepted. Chapter 2.

Type Checking

isnumber(value): true if the value is a number.

isstring(value): true if the value is a string.

isbool(value): true if the value is a boolean.

isempty(value): true if the value is empty.

isarray(value): true if the value is an array.

Shared by Strings and Arrays

length(value): Returns the number of characters in a string, or the number of items in an array. Chapters 5 and 7.

contains(collection, value): For a string, checks whether it contains another string, case-sensitively. For an array, checks whether any item equals the given value. Chapter 7.

String Functions

upper(string): Converts a string to uppercase. Chapter 7.

lower(string): Converts a string to lowercase. Chapter 7.

lower("PIANO")   // "piano"

trim(string): Removes whitespace from the start and end of a string, leaving the middle untouched. Chapter 7.

replace(string, old, new): Replaces every occurrence of old with new. Chapter 7.

split(string, delimiter): Breaks a string into an array of pieces, wherever the delimiter appears. Chapter 7.

split("take candle", " ")   // ["take", "candle"]

substring(string, start, length): Returns part of a string, starting at position start for length characters.

startswith(string, prefix): true if the string begins with prefix, case-sensitively. Chapter 7.

endswith(string, suffix): true if the string ends with suffix, case-sensitively. Chapter 7.

Math Functions

abs(number): Absolute value, strips a negative sign. Chapter 8.

pow(base, exponent): Raises base to the power of exponent. Chapter 8.

round(number): Rounds to the nearest whole number. Chapter 8.

floor(number): Always rounds down. Chapter 8.

ceiling(number): Always rounds up. Chapter 8.

sqrt(number): Square root. A negative input raises an error. Chapter 8.

min(a, b): Returns the smaller of two numbers. Chapter 8.

max(a, b): Returns the larger of two numbers. Chapter 8.

random(): Returns a random number from 0 up to, but not including, 1. Chapter 8.

randomint(min, max): Returns a random whole number, inclusive of both min and max. Both must be whole numbers. Chapter 8.

randomint(1, 100)

Array Functions

array(): Creates a new, empty array. Chapter 5.

array(size): Creates a new array with size slots, each filled with empty. size must be a whole number, zero or greater.

append(array, value): Adds value to the end of the array, in place. Chapter 5.

remove(array, index): Removes the item at index, in place. index must point to an existing item. Chapter 5.

insert(array, index, value): Inserts value at index, in place. index may be anywhere from 0 up to and including the array's current length. Chapter 5.

reverse(array): Reverses the array in place, and also returns it.

sort(array): Sorts the array in place, and also returns it.

Special Object

last_error: Always available, holds three properties about the most recently caught error: last_error.message (the error text), last_error.line (the source line), and last_error.code (a short category code). Resets before each ordinary statement; populated when an attempt block catches an error. In most cases, naming a variable after error in an attempt block is simpler and does the same job. Chapter 10.