📝 variables entry to the guide.
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@ -102,5 +102,71 @@ tuples, with the addition of concatenation (``+``) and duplication (``*``) opera
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[3, 6, 8][1] # returns 6
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[3, 6, 8][1] # returns 6
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"love" in ["love", "pizzas"] # returns true
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"love" in ["love", "pizzas"] # returns true
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To access an array value, the operator ``[]`` can be used.
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For instance, syntax ``[3]`` means: "give me the third element".
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Arrays can be nested, that's why the operator ``[]`` can take several arguments.
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As an example, let's consider the following syntax ``[1, 2, 3]``
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means: "give me the third element of the second element of the first element of my array".
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.. code-block::
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:caption: array
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[[1, 2], [3, 4]] [0, 1] # equals 2
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[[1, 2], [3, 4]] [0, 0] # equals 1
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[[1, 2], [3, 4]] [1, 1] # equals 4
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Declaring variables
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-------------------
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Variables declaration is a fundamental feature of pratically all programming languages.
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Some use only mutable variables (like Python), and others allow the programmer
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to declare immutable variables (like C for instance).
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CCM offer two syntaxes for declaring variables:
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the ``var`` keyword is used to declare mutable variables, and the ``const``
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keyword declares immutable one.
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Storing expression using variables
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Variables are containers for storing expressions.
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To declare a variable, we use the keyword ``var``
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followed by the name of the variable as well as its value: ``var name = expr``.
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Variables can be reassigned later using the syntax ``name = expr``, and they can be
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used everywhere an expression can be.
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.. code-block::
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:caption: mutable variable declaration
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var x = 37
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x # equals 37
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x = 7
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x # equals 7
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Immutability using constants
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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A constant is an immutable values storage similaire to classical variables.
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The fundamental difference between constants and variables is mutability:
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variables can be reassigned, constants cannot.
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If you try to change the value of a constant, an error will be raised.
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.. code-block::
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:caption: immutable variable declaration
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const x = 37
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x # equals 37
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x = 7 # ILLEGAL
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Dereferencing arrays
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~~~~~~~~~~~~~~~~~~~~
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Variables can contain any expression, and in particular it could store an array.
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To access array elements, the operator ``[]`` can be used directly after the variable name.
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.. code-block::
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:caption: Array dereferencement
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var x = [2, 4, 6]
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x[1] # equals 4
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I
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