4.1 KiB
MinBasic guide
Keywords and case sensitivity
Most things in MinBasic are described with keywords.
These keywords are not case-sensitive, meaning that if x > 0 then is equivalent to IF x > 0 THEN.
User-defined things, like functions and variables, are case-sensitive. So myVariable, MYVARIABLE and myvariable all refer to different things.
We recommend to prefer uppercase for keywords and lowercase for variable names.
Comments
Comments are prefixed with the REM keyword.
Variables and assignments
To assign a value to a variable, use the variable = value syntax, where value can be any expression.
Optionally, you can prefix the assignment with the LET keyword.
To use a variable, simply put its name in an expression.
Note: multi-line expressions are not yet supported.
Variables don't need to be declared, and values can be assigned to them at any point in time.
Using a variable before it was assigned any value will yield null instead.
Examples
REM Sets the variable "answer" to 42:
answer = 42
REM Also sets the variable "answer" to 42:
LET answer = 42
REM Sets the variable "x" to 21:
x = answer / 2
REM Increments "x" by one:
x = x + 1
Expressions
The following binary operators are supported:
- Addition:
a + b - Subtraction:
a - b - Multiplication:
a * b - Division:
a / b - Modulo:
a % b - Less than:
a < b - Greater than:
a > b - Less than or equal:
a <= b - Greater than or equal:
a >= b - Equal:
a == b - Not equal:
a != b
Multiplication and division have a greater precedence than addition and subtraction. Comparisons have the lowest precedence. You can wrap sub-expressions in parentheses to override precedence.
Some additional operators are only available by calling builtin functions, which are case-insensitive:
- Maximum:
MAX(a, b) - Minimum:
MIN(a, b) - Square root:
SQRT(a) - Floor:
FLOOR(a) - Ceil:
CEIL(a) - Round:
ROUND(a) - Rand:
RAND(a), generates a random number between0anda
Examples
REM Picks a random integer between 0 and 63
n = FLOOR(RAND(64))
REM Sets x to the remainder of n by 8, and y by the integer part of n / 8
x = n % 8
y = FLOOR(n / 8)
REM Sets dist to the euclidean distance between (0, 0) and (x, y)
dist = SQRT(x * x + y * y)
Jumps and labels
Jumping allows you to interrupt the regular flow of instruction to go to another point in the program.
To perform a jump, you will first need to define where you want to jump to. You have two options: prefixing a line with a number, or writing a named label.
Then, use the GOTO statement to jump to either a line number, or a label.
Using line numbers
REM The following lines have been numbered. The numbers chosen are arbitrary, but they are commonly increasing multiples of 10,
REM which allows you to squeeze in debugging statements when needed.
10 PRINT "Hello, world"
20 PRINT "This is line 20"
REM We then jump back to line 20, which will cause an infinite loop printing "This is line 20"
30 GOTO 20
Using labels
REM We define here the "start" label
start:
PRINT "Hello, world"
REM We then jump to the "start" label, causing an infinite loop printing "Hello, world"
GOTO start
Conditions
The IF keyword allows you to execute different parts of the code depending on whether a condition is met or not.
The syntax for IF is as follows:
IF condition THEN
REM Code to be executed if "condition" is true
ELSE
REM Code to be executed if "condition" is false
END IF
If you do not need to execute code when the condition is false, then you can omit the ELSE keyword.
Example
REM This is a condition without an ELSE block:
IF age < 0 THEN
PRINT "It seems like you weren't born yet..."
END IF
IF age < 18 THEN
PRINT "You are underaged"
ELSE
REM We can nest conditions within other conditions:
IF age == 18 THEN
PRINT "You just turned 18!"
ELSE
PRINT "You're over 18"
END IF
END IF