Ruby condition control structure

 

I. Comparison statements

Most of them are the same as other languages. Note <=>,

 

Condition Statement

The following forms

• If
• If... else... end
• If... elsif... else... end
• Unless (if not)
• Case... when

x=1if x==1    puts 1elsif x==2    puts 2else     puts  3end

Note that elsif is not elseif. Compared with C, an end is added..

 

However, the case statement of Ruby differs greatly from the C/C ++ format:

Case when the judgment item when comparison value then code else code end

    def [](index)        case index            when 0, -2 then @x            when 1,-1  then @y            when :x,"x" then @x            when :y,"y" then @y            else nil        end    end

P [0], p [-2] returns x

For example, the following two sections of code are equivalent, but the code using case is clearer:

if var < 60  print "failed/n"elsif var < 70  print "passed/n"elsif var < 80  print "good/n"elsif var < 90  print "great/n"else  print "excellent/n"endcase var  when 0..59 then print "failed/n"  when 60..69 then print "passed/n"  when 70..79 then print "good/n"  when 80..89 then print "great/n"  else print "excellent/n"end

 

Loop iteration statement

X. Times

 

X. updo, X. downto, X. Step (limit, steplength)

 

: Loop statement

Loop

Break jumps out of the entire Loop

Http://www.cnblogs.com/cnblogsfans/archive/2009/02/05/1384944.html