Ruby_day[1]控制流(if, unless)

summary：

　　1: if, elsif, else.注意结束if时后面加end

　　2: unless, else

 

• How to use if, else, and elsif
• How to use comparators / relational operators like ==(相等), !=（不等）, <, <=, >, and >=

How to use boolean / logical operators like &&（与）, ||（或）, and !（非）

1 a = 10
2 b = 11
3 if a < b
4   print "a is less than b!"
5 elsif b > a
6   print "b is less than a!"
7 else
8   print "b is equal to a!"
9 end

 

1 problem = false
2 print "Good to go!" unless problem
3 #除非有问题（problem=true时不打出来），否则打印出来

 

多个逻辑运算结合，用括号 括起来

1 ( 1 == 1 ) && ( 2 == 2 )  // true
2 ( 1 == 2 ) || ( 2 == 2 ) // true
3 !( false ) // true

 

转载于:https://www.cnblogs.com/jypwn/p/4044231.html