Ruby Concise Learning Notes (i): strings, numbers, classes, and objects _ruby topics

To prove that Ruby really works, Hello World can write so succinctly:

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Puts ' Hello World '

1. Input/output

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Print (' Enter your name ')
Name=gets ()
Puts ("Hello #{name}")

Note: Ruby is case-sensitive

2.String class

The variable name in puts ("Hello #{name}") is embedded in the entire string, evaluated by the #{} package, and wrapped in double quotes "" (If only single quotes "only returns the literal value)." Not only are variables, you can even embed "T" "\ n" and an arithmetic expression.

Copy Code code as follows:

Puts "Hello #{showname}"
Puts ("\n\t#{(1+2) * 3}\ngoodbye")

3.if......then statement

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TaxRate = 0.175
print ' Enter price (ex tax): "
s = gets
Subtotal = S.to_f
if (Subtotal < 0.0) Then
Subtotal = 0.0
End
Tax = Subtotal * TaxRate
Puts ' Tax on $#{subtotal} ' is $#{tax}

1. Each if must have an end corresponding to it, and then optional unless it is on the same line as if.
The 2.to_f () method returns the floating-point number itself for a string with a value of floating-point numbers, which returns 0.0 for the person who cannot convert

The difference between 4.val, $val, @val

Val is a local variable, $val is a global variable, @val is an instance variable

Instance variables are equivalent to member variables

5. How to define a class

Look at two pieces of code

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Class Dog
def set_name (Aname)
@myname = Aname
End

def get_name
Return @myname
End

Def talk
Return ' woof! '
End
End

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Class Treasure
Def initialize (Aname, adescription)
@name = Aname
@description = Adescription
End

def to_s # Override default To_s method
"The #{@name} treasure is #{@description}\n"
End
End

1. Member variable needs @ Mark
2. No parameter method can be added without ()
3. Each class ends with end
4. The default has no parameter constructor initialize (), or you can override initialize with parameters ()