Editing Squirrel Operators

Now that you know how to create data and store it into variables, we can now go over how to modify and operate on that data. Operators are used for this purpose, they take one or more operands and produce a result value. Operators which take one operand are called unary operators, two operands are binary operators, and three are ternary operators.
This section is quite long so don't worry about memorizing every single operator, just browse through and become familiar with the various types of operators and their uses, you'll have plenty of examples throughout the rest of the guide to work with.


<hr>


<span style="font-size:120%">'''Arithmetic'''</span>

'''Unary Operators'''
{| class="wikitable" style="width:100%; margin:auto; text-align:center font-weight:bold; font-size:110%"
|+
!Operator
!Symbol
!Form
!Operation
|- style="text-align:center"
|Unary minus
| -
| -x
|Negation of x
|}

<syntaxhighlight lang="c#" line="1" start="1" style="font-weight:bold;>
local x = 50;
x = -x; // -50
</syntaxhighlight>


'''Binary Operators'''
{| class="wikitable" style="width:100%; margin:auto; text-align:center font-weight:bold; font-size:110%"
|+
!Operator
!Symbol
!Form
!Operation
|- style="text-align:center"
|Addition
| +
| x + y
|x plus y
|- style="text-align:center"
|Subtraction
| -
| x - y
|x minus y
|- style="text-align:center"
|Multiplication
| *
| x * y
|x multiplied by y
|- style="text-align:center"
|Division
| /
| x / y
|x divided by y
|- style="text-align:center"
|Remainder
| %
| x % y
|the remainder from: x divided by y
|}

<syntaxhighlight lang="c#" line="1" start="1" style="font-weight:bold;>
local v = 100 + 100; // 200
local w = 0 - 2;     // -2
local x = 5.5 * 100; // 550.0
local y = 20 / 2;    // 10
local z = 23 % 2;    // 1
</syntaxhighlight>

The addition operators <code>'''+'''</code> and <code>'''+='''</code> are also able to handle string operands. If one operand is a string, Squirrel will try to convert the other operand to a string as well.
This same type conversion happens between floats and integers for any arithmetic operator (not just addition). If one operand is a float and the other an integer, the resulting value will be a float.

<syntaxhighlight lang="c#" line="1" start="1" style="font-weight:bold;>
local str1 = "Hello,";
local str2 = " World!";
str1 += str2; // Hello World!
// See next section for +=

local float = 10 - 7.0 // 3.0
</syntaxhighlight>


<hr>


<span style="font-size:120%">'''Assignment'''</span>

{| class="wikitable" style="width:100%; margin:auto; text-align:center font-weight:bold; font-size:110%"
|+
!Operator
!Symbol
!Form
!Operation
|- style="text-align:center"
|Assignment
| =
| x = y
|assign value y to variable x
|- style="text-align:center"
|Addition Assignment
| +=
| x += y
|assign x + y to variable x
|- style="text-align:center"
|Subtraction Assignment
| -=
| x -= y
|assign x - y to variable x
|- style="text-align:center"
|Multiplication Assignment
| *=
| x *= y
|assign x * y to variable x
|- style="text-align:center"
|Division Assignment
| /=
| x /= y
|assign x / y to variable x
|- style="text-align:center"
|Remainder Assignment
| %=
| x %= y
|assign x % y to variable x
|- style="text-align:center"
|}

<syntaxhighlight lang="c#" line="1" start="1" style="font-weight:bold;>
local x = 100;
x += 5;   // equivalent to: x = x + 5
x -= 5;   // 100
x *= 100; // 10,000
x /= 2;   // 5,000
x %= 2;   // 0
</syntaxhighlight>


<hr>


<span style="font-size:120%">'''Increment/Decrement'''</span>
{| class="wikitable" style="width:100%; margin:auto; text-align:center font-weight:bold; font-size:110%"
|+
!Operator
!Symbol
!Form
!Operation
|- style="text-align:center"
|Pre-increment
| ++
| ++x
|increment x by 1, then return x
|- style="text-align:center"
|Post-increment
| ++
| x++
|copy x, increment variable x by 1, then return the copy
|- style="text-align:center"
|Pre-decrement
| --
| --x
|decrement x by 1, then return x
|- style="text-align:center"
|Post-decrement
| --
| x--
|copy x, decrement variable x by 1, then return the copy
|}

<syntaxhighlight lang="c#" line="1" start="1" style="font-weight:bold;>
local x = 1;
local y;

y = x++; // y = 1, it got the value of x and then x got incremented, x = 2
y = ++x; // y = 3, x got incremented and then y got x's value
</syntaxhighlight>


<hr>


<span style="font-size:120%">'''Relational'''</span>
{| class="wikitable" style="width:100%; margin:auto; text-align:center font-weight:bold; font-size:110%"
|+
!Operator
!Symbol
!Form
!Operation
|- style="text-align:center"
|Equality
| ==
| x == y
|true if x equals y, false otherwise
|- style="text-align:center"
|Inequality
| !=
| x != y
|true if x does not equal y, false otherwise
|- style="text-align:center"
|Less than
| <
| x < y
|true if x is less than y, false otherwise
|- style="text-align:center"
|Greater than
| >
| x > y
|true if x is greater than y, false otherwise
|- style="text-align:center"
|Less than or equal to
| <=
| x <= y
|true if x is less than or equal to y, false otherwise
|- style="text-align:center"
|Greater than or equal to
| >=
| x >= y
|true if x is greater than or equal to y, false otherwise
|}

<syntaxhighlight lang="c#" line="1" start="1" style="font-weight:bold;>
local x = 5;
local y = 5;
local z;

z = x == y; // true
z = x != y; // false
z = x > y;  // false
z = x >= y; // true
z = x < y;  // false
z = x <= y; // true
</syntaxhighlight>


<span style="font-size:120%">'''Logical'''</span>
{| class="wikitable" style="width:100%; margin:auto; text-align:center font-weight:bold; font-size:110%"
|+
!Operator
!Symbol
!Form
!Operation
|- style="text-align:center"
|Logical NOT
| !
| !x
|true if x evaluates to false, otherwise false
|- style="text-align:center"
|Logical AND
| &&
| x && y
|true if both operands evaluate to true, otherwise false
|- style="text-align:center"
|Logical OR
| <nowiki>||</nowiki>
| x <nowiki>||</nowiki> y
|true if either operand evaluates to true, otherwise false
|}

For most purposes the above definitions for AND & OR are sufficient, however Squirrel does not simply return boolean true or false for these operators, rather it returns a specific operand passed to the operator based on the result.

Logical AND, if either operand evaluates to false, will return the '''first''' operand that evaluates to false. Otherwise if both evaluate true the operator will return the '''last''' operand.

Logical OR will return the first operand that evaluates to true, if none do, it will return the '''last''' operand.


Certain values evaluate to false, these are: <code>'''false, null, 0, 0.0'''</code>. Everything else evaluates to true.

<syntaxhighlight lang="c#" line="1" start="1" style="font-weight:bold;>
local v = 0 && 1;         // 0
local w = null || "bark"; // "bark"
local x = "" || true;     // ""
local y = !0;             // true
local z = 5 && "0"        // "0"
</syntaxhighlight>

<span style="font-size:120%">'''Bitwise'''</span>

&, |, ^, ~, <<, >>, >>>

<span style="font-size:120%">'''Other Operators'''</span>

in, instanceof, typeof, comma, ternary


<span style="font-size:120%">'''Operator Precedence'''</span>

-, ~, !, typeof , ++, -- 	highest
/, *, % 	…
+, - 	 
<<, >>, >>> 	 
<, <=, >, >=, instanceof 	 
==, !=, <=> 	 
& 	 
^ 	 
&&, in 	 
+=, =, -=, /=, *=, %= 	…
, (comma operator) 	lowest

IntegerLiteral        ::=  [1-9][0-9]* | '0x' [0-9A-Fa-f]+ | ''' [.]+ ''' | 0[0-7]+
FloatLiteral          ::=  [0-9]+ '.' [0-9]+
FloatLiteral          ::=  [0-9]+ '.' 'e'|'E' '+'|'-' [0-9]+
StringLiteral         ::=  '"'[.]* '"'
VerbatimStringLiteral ::=  '@''"'[.]* '"'