Explain in detail the condition judgment statements in Ruby and explain the ruby judgment statements

Explain in detail the condition judgment statements in Ruby and explain the ruby judgment statements

Ruby provides conditional structures, which are common in modern programming languages. Here, we will explain all the Ruby conditional statements and modifiers.
Ruby if... else statement:
Syntax:

if conditional [then]  code...[elsif conditional [then]  code...]...[else  code...]end

If expression is used for conditional execution. Values false and nil are both false, and others are true. Note that the Ruby string uses elsif, neither else if nor elif.

If the condition is true, the code is executed. If the condition is not true, the Code specified in the else clause is executed.

If expressions are reserved words, a linefeed or semicolon is used to separate the code.
Instance:

#!/usr/bin/rubyx=1if x > 2  puts "x is greater than 2"elsif x <= 2 and x!=0  puts "x is 1"else  puts "I can't guess the number"endx is 1

Ruby if rhetoric:
Syntax:

Code if condition

The if condition is true.
Instance:

#!/usr/bin/ruby$debug=1print "debug\n" if $debug

This produces the following results:

debug

Ruby unless statement:
Syntax:

unless conditional [then]  code[else  code ]end

If the condition is false, run the code. If the condition is false, the Code specified in the else clause is executed.
For example:

#!/usr/bin/rubyx=1unless x>2  puts "x is less than 2" else puts "x is greater than 2"end

This produces the following results:

x is less than 2

Ruby unless rhetoric:
Syntax:

Code unless conditional

Run the Code. If conditions exist, the code is false.
Instance:

#!/usr/bin/ruby$var = 1print "1 -- Value is set\n" if $varprint "2 -- Value is set\n" unless $var$var = falseprint "3 -- Value is set\n" unless $var

This produces the following results:

1 -- Value is set3 -- Value is set

Ruby case statement
Syntax:

case expression[when expression [, expression ...] [then]  code ]...[else  code ]end

When a comparison expression is specified, the Code executed when the = Operator is used to match the specified terms.

Clause calculates the expressions specified by the when and left operands. If no clause matches, the Code else clause is executed.

If the expression of the when statement is reserved, A linefeed or semicolon is used to separate the code.

So:

case expr0when expr1, expr2  stmt1when expr3, expr4  stmt2else  stmt3end

It is basically similar to the following:

_tmp = expr0if expr1 === _tmp || expr2 === _tmp  stmt1elsif expr3 === _tmp || expr4 === _tmp  stmt2else  stmt3end

Instance:

#!/usr/bin/ruby$age = 5case $agewhen 0 .. 2  puts "baby"when 3 .. 6  puts "little child"when 7 .. 12  puts "child"when 13 .. 18  puts "youth"else  puts "adult"end

This produces the following results:

little child