break,next,redo,retry的应用

=begin
break ， next , redo , retry
在循环体内，如果遇到：
break ，跳出当层循环；
next ，忽略本次循环的剩余部分，开始下一次的循环；
redo ，重新开始循环，还是从这一次开始；
retry ，重头开始这个循环体
=end


#break示例
puts "演示break"
c='a'
for i in 1..4
if i == 2 and c =='a'
c = 'b'
print "\n"
break
end
print i,c," "
end
puts "\n\n"

#next示例
puts "演示next"
c='a'
for i in 1..4
if i == 2 and c =='a'
c = 'b'
print "\n"
next
end
print i,c," "
end
puts "\n\n"


#redo示例
puts "演示redo"
c='a'
for i in 1..4
if i == 2 and c =='a'
c = 'b'
print "\n"
redo
end
print i,c," "
end
puts "\n\n"

#retry示例
puts "演示retry"
c='a'
for i in 1..4
if i == 2 and c =='a'
c = 'b'
print "\n"
retry
end
print i,c," "
end
puts "\n\n"