Touhou Danmakufu: Values and Variables

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Values

Numbers

0
345
12.34
0.12345

Normal real numbers.

Boolean values

true
false

True or false as value. In numerical expressions such as true + 1 and false x 5 - 2, true and false are taken as 1 and 0 respectively. However, as of v0.12m of Danmakufu, they cannot be compared with other numerical expressions, e.g. conditionals like true == 1 and false > 0 will not parse.

Characters

'A'
'E'
'あ'

One letter. Japanese character can be used.

Arrays

[3, 1, 4, 1, 5, 9]
[true, false, true, true, false]

Array of values. Multidimensional arrays can be used, e.g.

let Array = [ [3, 1, 4], [1, 5, 9] ];

the entry Array[1][2] will then have the value 9. To change the value of Array[1][2], v0.12m of Danmakufu will not parse

Array[1][2] = 8;  //this is wrong

One way to do this is

Array[1] = [1, 5, 8];  //this is correct

i.e. you can only change entries that are one level deep. 'Mixed-entry' arrays are not allowed, e.g.

 Array = [ [3, 1, 4], [1, 5] ];  //these are wrong
 Array2 = [ [3, 1, 4], 1 ];

will not parse. The entries in an array must all be of the same kind.

You can concantenate arrays

 [3, 1, 4] ~ [1, 5, 9];

this gives the single array

 [3, 1, 4, 1, 5, 9]

You can also erase entries from arrays

 erase([3, 1, 4, 1, 5, 9], 2);

this gives the shortened array

 [3, 1, 1, 5, 9]

Strings

"Hello, world!"
"Test Sign 'Test'"
"試符「テスト」"

Arrays of characters.

\"

describes a string literal which contains only a letter ".

Variable Definitions

let ImgBoss = "script\img\ExRumia.png";
let frame   = -120;
let array   = [3, 1, 4, 1, 5, 9];

Variables are storages of values. let is used to define variables.

let (variable name);
let (variable name) = (initial value);

The variable name consists of alphabets, figures, and underscore (_), but it cannot begin with figures. The initialization of the variable can be omitted.

Expressions

Numerical Expressions

6 * 2 + (4 - 3) * 9
x ^ 2 + 3 % x + 8

Standard numerical expressions. The priority of operators is common-sense. Variables can be used in the expressions.

Conditional Expressions

frame == 10
! (x < y && y < z)

Standard conditional expressions. The results of the conditional expressions are boolean values. Note that "if equal" is not '=' but '=='. For the meanings of the operators, refer to the Priority of Operators subsection.

Indexing Expressions

[3, 1, 4, 1, 5, 9][2]
array[i]

Get an element of the array with the index.

array[1..4]

A slice of the array can be extracted.

(array)[(index)]
(array)[(first index)..(last index)]

Array Calculations

[3, 1, 4] + [1, 5, 9]
array1 + array2

Each element is calculated, e.g. [3, 1, 4] + [1, 5, 9] is [4, 6, 13].

String Expressions

"script\img\ExRumia.png"
ImgFolder ~ "ExRumia.png"

Operator '~' concatenates two arrays (of course strings, too). String leterals can be concatenated without ~ operators as

"Wave Sign " \" "Mind Shaker" \"

which is such a string as

Wave Sign "Mind Shaker"

Priority of Operators

High Priority

• ( )

  Parentheses

  (| |)

  Absolute value

• [ ]

  Indexing, Slicing

  ^

  Power

• +

  Plus sign

  -

  Minus sign

  !

  Conditional not

• *

  Multiplication

  /

  Division

  %

  Modulo (Remainder)

• +

  Addition

  -

  Subtraction

  ~

  Concatenation

• ==

  Equal to

  !=

  Not equal to

  <

  Less than

  <=

  Less than or equal to

  >

  Greater than

  >=

  Greater than or equal to

• &&

  Conditional and

  ||

  Conditional or

Low Priority

Assignment Statements

Simple Assignment Statements

y = x ^ 2 + 3 * x + 8;
frame = 0;
array[2] = 4;

Change the left-side variable contents with right value.

(variable) = (expression);

Compound Assignment Statements

x += 3;
y *= 2;

Operate right value to the left-hand variable and assign the result into the variable. e.g.

x += 3;

adds 3 to x, and

y *= 2;

multiplies 2 to y.

(variable) (binary numerical operator)= (expression);

Increment/Decrement

frame++;

Add 1 to the variable.

i--;

Subtract 1 from the variable.

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