Ruby on Rails 入门之：(8) Ruby中条件语句

Ruby on Rails 入门之：(8) Ruby中条件语句1. if语句

if语句是示例如下：

[ruby]view plaincopy

1.#encoding:gbk

2.FAN = 10;

3.if FAN>5

4. puts "FAN > 5";

5.elsif FAN>3

6. puts "3 < FAN < 5";

7.else

8. puts "FAN < 3";

9.end

2. unless语句

unless语句和if相反，如果条件不成立则执行

[ruby]view plaincopy

1.#encoding:gbk

2.FAN = 10;

3.if FAN>5

4. puts "FAN > 5";

5.elsif FAN>3

6. puts "3 < FAN < 5";

7.else

8. puts "FAN < 3";

9.end

10.

11.puts "*******************************";

12.

13.puts "unless test"unless FAN > 20; 3. case语句

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1.#encoding:gbk

2.FAN = 10;

3.if FAN>5

4. puts "FAN > 5";

5.elsif FAN>3

6. puts "3 < FAN < 5";

7.else

8. puts "FAN < 3";

9.end

10.

11.puts "*******************************";

12.

13.puts "unless test"unless FAN > 20;

14.

15.puts "*******************************";

16.

17.NUM = 6;

18.case NUM

19.when 5

20. puts "5";

21.when 6

22. puts "6";

23.end

case语句中的when 还可以是一个范围。

4. while循环

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1.#encoding:gbk

2.FAN = 10;

3. a = 1;

4.

5.while a < FAN do

6. puts a;

7. a=a+1;

8.end

Ruby中不支持++运算符

5. for循环

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1.#encoding:gbk

2.FAN = 10;

3. a = 1;

4.

5.while a < FAN do

6. puts a;

7. a=a+1;

8.end

9.

10.FOODS = ["巧克力","面包","蛋糕","牛奶"];

11.for f in FOODS do

12. puts f;

13.end

还可以遍历Hash对象

[ruby]view plaincopy

1.#encoding:gbk

2.FAN = 10;

3. a = 1;

4.

5.while a < FAN do

6. puts a;

7. a=a+1;

8.end

9.

10.FOODS = ["巧克力","面包","蛋糕","牛奶"];

11.for f in FOODS do

12. puts f;

13.end

14.

15.Stus = {"小王"=>"29","小李"=>"23","小宋"=>"25"};

16.

17.for name,age in Stus do

18. puts name, age;

19.end

6. 迭代器

使用数组或者Hash对象自带的迭代器

[ruby]view plaincopy

1.#encoding:gbk

2.FAN = 10;

3. a = 1;

4.

5.

6.

7.FOODS = ["巧克力","面包","蛋糕","牛奶"];

8.FOODS.each do |f|

9. puts f;

10.end

11.

12.Stus = {"小王"=>"29","小李"=>"23","小宋"=>"25"};

13.Stus.each do |name,age|

14. puts name,age;

15.end

7. 循环控制

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1.loop{

2. puts "(((((((((((((((())))))))))))))))))))":

3. i=i+1;

4.if(i>3)

5.break;

6.end

7.}

使用loop创建一个基本的循环。

其他的循环控制：

next : 终止当前的循环，进入下一个循环，相当与其他编程语言的continue;

redo : 跳出本次循环，进入下一次循环，使用redo语句跳入下一次循环的时候，不检查条件是否成立，直接进入循环。

return : 结束循环