2.2. Values and Data types
While Squirrel is a dynamically typed language and variables do not have a type, different operations may interpret the variable as containing a type. Squirrel’s basic types are integer, float, string, null, table, array, function, generator, class, instance, bool, thread and userdata.
2.2.1. Integer
An Integer represents a 32 bit (or better) signed number.:
local a = 123 //decimal
local b = 0x0012 //hexadecimal
local c = 075 //octal
local d = 'w' //char code
2.2.2. Float
A float represents a 32 bit (or better) floating point number.:
local a=1.0
local b=0.234
2.2.3. String
Strings are an immutable sequence of characters. In order to modify a string is it necessary create a new one.
Squirrel’s strings are similar to strings in C or C++. They are
delimited by quotation marks("
) and can contain escape
sequences (\t
, \a
, \b
, \n
, \r
, \v
, \f
,
\\
, \"
, \'
, \0
, \x<hh>
, \u<hhhh>
and
\U<hhhhhhhh>
).
Verbatim string literals do not interpret escape sequences. They begin
with @"
and end with the matching quote. Verbatim string literals
also can extend over a line break. If they do, they include any white
space characters between the quotes:
local a = "I'm a wonderful string\n"
// has a newline at the end of the string
local x = @"I'm a verbatim string\n"
// the \n is literal, similar to "\\n" in a regular string.
However, a doubled quotation mark within a verbatim string is replaced by a single quotation mark:
local multiline = @"
this is a multiline string
it will ""embed"" all the new line
characters
"
2.2.4. Null
The null value is a primitive value that represents the null, empty, or non-existent reference. The type Null has exactly one value, called null.:
local a = null
2.2.5. Bool
Bool is a double-valued (Boolean) data type. Its literals are true
and false
. A bool value expresses the validity of a condition
(tells whether the condition is true or false).:
local a = true;
2.2.6. Table
Tables are associative containers implemented as a set of key/value pairs called slots.:
local t={}
local test=
{
a=10
b=function(a) { return a+1; }
}
2.2.7. Array
Arrays are simple sequence of objects. Their size is dynamic and their index always starts from 0.:
local a = ["I'm","an","array"]
local b = [null]
b[0] = a[2];
2.2.8. Function
Functions are similar to those in other C-like languages with a few key differences (see below).
2.2.9. Class
Classes are associative containers implemented as sets of key/value pairs. Classes are created through a ‘class expression’ or a ‘class statement’. class members can be inherited from another class object at creation time. After creation, members can be added until an instance of the class is created.
2.2.10. Class Instance
Class instances are created by calling a class object. Instances, as tables, are implemented as sets of key/value pairs. Instance members cannot be dynamically added or removed; however the value of the members can be changed.
2.2.11. Generator
Generators are functions that can be suspended with the statement ‘yield’ and resumed later (see Generators).
2.2.12. Userdata
Userdata objects are blobs of memory or pointers defined by the host application but stored within Squirrel variables (See Userdata and UserPointers).
2.2.13. Thread
Threads are objects representing a cooperative thread of execution, also known as coroutines.
2.2.14. Weak Reference
Weak References are objects that point to another (non-scalar) object but do not own a strong reference to it. (See Weak References).