Ruby | Symbol Class - GeeksforGeeks

The objects of the Symbol class represent the names present inside the Ruby interpreter. They are usually generated by using :name literal syntax or by using to_sym methods. The similar Symbol objects are created for a given name string for the duration of a program's execution, regardless of the content and meaning of the name. Example:

Ruby

# Ruby program to illustrate 
# Symbol objects

# context 3
module Geeks1

class Max
end
$a1 = :Max
end

# context 1
module Geeks2

Max = 1
$a2 = :Max
end

# context 2
def Max()

end

$a3 = :Max

puts $a1.object_id 
puts $a2.object_id 
puts $a3.object_id

Output:

1675428
1675428
1675428

Explanation: If Max is a constant in context1, a method in context2, or class in the context3, then this :Max will be the same object in all given contexts.

Class Method

all_symbols : This method returns an array of symbols that currently present in the Ruby's symbol table.

Symbol.all_symbols

Example:

Ruby

# Ruby program to illustrate 
# the use of all_symbol method

# Using all_symbol method
puts Symbol.all_symbols.size 
puts Symbol.all_symbols[1, 20]

Output:

3250
"
#
$
%
&
'
(
)
*
+
,
-
.
/
:
;
<
=
>
?

Instance Methods

id2name : This method returns a string that is representation of sym.

sym.id2name

Example:

Ruby

# Ruby program to illustrate 
# the use of id2name method

# Using id2name method
p :Geeks.id2name 
p :"Welcome to GeeksforGeeks Portal".id2name

Output:

"Geeks"
"Welcome to GeeksforGeeks Portal"

inspect : This method return the representation of sym in the form of symbol literal.

sym.inspect

Example:

Ruby

# Ruby program to illustrate 
# the use of inspect method

# Using inspect method
p :geeks.inspect
p :"welcome to geeksforgeeks portal".inspect

Output:

":geeks"
":\"welcome to geeksforgeeks portal\""

to_s : This method is similar to Symbol#id2name. This method returns the name or a string that corresponding to sym.

sym.to_s

Example:

Ruby

# Ruby program to illustrate 
# the use of to_s method

# Using to_s method
p :geeks.to_s
p :"welcome to geeksforgeeks portal".to_s

Output:

"geeks"
"welcome to geeksforgeeks portal"

<=> :It compares sym to other_sym after calling to_s. It returns -1 if sym is less than other_sym, it returns 0 if sym is equal to other_sym, or it returns +1 if sym is greater than other_sym.
```
sym <=> other_sym 
```
Example:
Ruby
# Ruby program to illustrate # use of <=> # Using <=> a= :geeks b = :"welcome to geeksforgeeks portal" puts a<=>b c= :geeks puts a<=>c puts b<=>a
Output:
```
-1
0
1
```

== : It returns true if the sym is equal to obj, otherwise it return false.

sym== obj

Example:

Ruby

# Ruby program to illustrate 
# use of ==

# Using ==
a= :geeks
b = :"welcome to geeksforgeeks portal"
puts a==b
c= :geeks
puts a==c

Output:

false
true

[] : This method returns the value of sym.to_s[].
```
sym[idx] --> char 
sym[b, n] --> string
```
capitalize : This method is similar to Symbol#to_s.
```
sym.capitalize
```
casecmp : This method is case-insensitive version of symbol <=$gt;. It will return -1, 0, 1, or nil. It is worked on A-Z/a-z, not on all Unicode. In this method nil is returned when the two symbols have incompatible encodings or if other_sym is not a symbol.
```
sym.casecmp(other)
```
Example:
Ruby
# Ruby program to illustrate # use of casecmp method # Using casecmp method puts :GeeKs.casecmp(:geeks) puts :GeeKsGfg.casecmp(:geeksG) puts :GeeKsGfg.casecmp(:geeksGfgz) puts :GeeKsGfg.casecmp(3)
Output:
```
0
1
-1
nil
```

downcase : This method converts upper-case letters in lower-case.

sym.downcase

Example:

Ruby

# Ruby program to illustrate 
# use of the downcase method

# Using the downcase method
puts :"WELCOME TO GEEKSFORGEEKS".downcase

Output:

:"welcome to geeksforgeeks"

length : This method returns the length of the given sym.

sym.length

Example:

Ruby

# Ruby program to illustrate 
# use of length method

# Using length method
puts :GeeKsGfg.length

Output:

slice : This method is similar to Symbol#to_s. This method provides you character on the given index from the sym .

sym.slice(index)
sym.slice(b, n)

Example:

Ruby

# Ruby program to illustrate 
# use of slice method

# Using slice method
p :GeeKsGfg.slice(3)
p :GeeKsGfg.slice(6)

Output:

"K"
"f"

swapcase : This method interchange the case of the characters that present in sym. In other words, it converts lower-case into upper-case and upper-case into lower-case.
```
sym.swapcase
```
Example:
Ruby
# Ruby program to illustrate # use of the swapcase method # Using swapcase method p "WELcome TO geeksFORGEEKS".swapcase
Output:
```
"welCOME to GEEKSforgeeks"
```

upcase : This method converts lower-case characters into upper-case.

sym.upcase

Example:

Ruby

# Ruby program to illustrate 
# use of the upcase method

# Using upcase method
p "welcome to geeksforgeeks".upcase

Output:

"WELCOME TO GEEKSFORGEEKS"

to_proc : This method return a Proc object which answer to the given method by sym.

sym.to_proc

Example:

Ruby

# Ruby program to illustrate 
# use of to_proc method

# Using to_proc method
p (1..5).collect(&:to_s)

Output:

 ["1", "2", "3", "4", "5"]

to_sym This method returns a symbol that corresponding to an object. Here sym has been already a symbol, so in this case it returns it.
```
sym.to_sym
```

Reference: https://ruby-doc.org/core-2.5.0/Symbol.html#method-i-5B-5D

Ruby | Symbol Class

Class Method

Instance Methods

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