Reserved Words in Ruby Programming Language

Reserved Words in any programming language are keywords whose meaning have been defined internally in the language itself. These words are not allowed to be used by Programmers as variable names or function names. If in case you do use these as variable/function names then during execution some error will be thrown.

Below is a table listing all of Reserved Words in Ruby Programming Language with description for each one.

Reserved Word	Description
BEGIN	Code enclosed in { } to run before program runs
END	Code enclosed in { } to run when program ends
alias	Create alias for existing method, operator, global variable
and	Logical AND Operator
begin	Begins a block of code
break	Terminate a loop
case	Comparing an expression with matching when clause which closes with end
class	Defining a class
def	Defining a function/method
defined?	To check if some variable, function exists or not
do	Begins a code block and execute code in the block, this ends with end keyword
else	Executes following code if previous conditional is not true
elsif	Executes following code if previous conditional is not true
end	For ending a code block which started with keywords like begin, class, def, do, if
ensure	Always execute at block termination
false	Logical Boolean false value
for	Begin a for loop
if	Executes the code block in case conditional statement for if is true
in	Used with for loop
module	Defining a module
next	Jump to point immediately before evaluation of loop’s conditional
nil	Empty or invalid or always false
not	Logical Negation Operator
or	Logical Or Operator
redo	Jump after a loop conditional
rescue	Evaluates the expression after an exception is raised
retry	• When called outside of rescue repates the method call • When called inside rescue jumps to top of block
return	Returns a value from a method or code block
self	Current Object
super	Calls method of same name in the superclass
then	Separator used with if, unless, when, case, rescue
true	Logical Boolean true
undef	Makes a method/function undefined in current class
until	Execute code block while conditional statement is false
when	Starts a clause under case statement
while	Executes the code block, until the conditional statement becomes false
yield	Executes the code block which is passed to a method

These are Reserved Words in Ruby Programming Language, while writing code in Ruby Language just don’t use these words as variables or functions names.

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