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116 lines
3.9 KiB
116 lines
3.9 KiB
Variables act as aliases to the values that we want them to represent and they allow us to access and manipulate the
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values that we assign to them.
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For example we could use the variable \pigVar{name} to represent the value \pigVal{"Brett Langdon"}.
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We do this with programming so that we can then access the value \pigVal{"Brett Langdon"} with a shorter representation, \pigVar{name}.
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\subsection{Declaration}
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To start with variables we need to declare their existence.
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By declaring a variable we are saying to the program, here is our alias and here is the value that we want it to represent.
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\begin{lstlisting}[caption={Variable Declaration}]
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a = 10
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print a
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\end{lstlisting}
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In the above example we are saying that we want to store the integer value \pigVal{10} into the variable \pigVar{a}.
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We can then use the variable \pigVar{a} to access the value \pigVal{10}.
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This program will output \pigOut{10} rather than \pigOut{a}.
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\par
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When we declare variables we are telling the programming language to allocate some space in your computers memory
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in order to store the value that you need it to.
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The amount of space needed to store each variable depends based on your specific language being used and which data
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type is being used to store the value.
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\subsection{Data Types}
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Programming languages support different types of data types or different types of values that they can represent in variables.
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Some programming languages use multiple different types of values but most of them support the basic types: string, integer (multiple kinds)
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and boolean (true or false).
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\begin{lstlisting}[caption={Data Types}]
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string = "Brett"
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integer = 10
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boolean = false
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\end{lstlisting}
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Please keep in mind that each programming language supports different data types and you should research those types to better
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understand variables in that language.
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As well some programming languages that are strickly typed which requires us to define the data type of the
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variable on declaration (unlike our sudo language).
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\subsection{Operators}
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Operators are symbols we can use to manipulate variables.
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There are a few different types of operators, Arithmetic, Comparison and Logical operators.
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A quick list of operators include:
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\begin{enumerate}
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\item Addition +
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\item Subtraction -
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\item Multiplication *
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\item Division /
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\item Equals =
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\item Equal To ==
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\item Not Equal To !=
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\item Less Than <
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\item Greater Than >
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\item Logical AND \&\&
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\end{enumerate}
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And there are more!
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\par
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Arithmetic operators include the mathematical symbols for addition (+), subtractions (-), division(/), multiplication(*) and equals(=).
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These operators are used to directly manipulate and change variables.
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For example we can add two variables together and then store that sum into a third variable.
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\begin{lstlisting}[caption={Addition Operator}]
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a = 10
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b = 5
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c = a + b
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print c
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\end{lstlisting}
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We store the value of \pigVal{10} into the variable \pigVar{a} and the value \pigVal{5} into the variable \pigVar{b}.
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Lastly, we store the sum of the variables \pigVar{a} and \pigVar{b} into the variable \pigVar{c}.
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The output of this program will be \pigOut{15}.
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\par
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Comparison operators are used to compare variables against other variables or values.
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The output of a comparison operator will be a boolean value (\pigVal{true} or \pigVal{false}).
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Some of the popular comparison operators are the equals to (==), not equals to (!=), less than (<), less than equal to (<=), greater than (>) and greater than equal to (>=).
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\begin{lstlisting}[caption={Comparison Operators}]
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name = ``Brett''
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a = 10
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b = 5
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c = a + b
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if name == ``Brett'':
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print ``Name is Brett''
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if a > 10:
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print ``A is greater than 10''
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if b >= 5:
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print ``B is greater than or equal to 5''
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if c != 6:
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print ``C is not 6''
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\end{lstlisting}
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In this example we are showing a few of the comparison operators.
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The output of this code will be:\\*
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\pigOut{Name is Brett\\*
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B is greater than or equal to 5\\*
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C is not 6}.
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\subsection{Conclusion}
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