ruby 语法(转）

转自 http://www.2cto.com/kf/201210/159906.html

1. if语句

if语句是示例如下：

[ruby]
#encoding:gbk
FAN = 10;
if FAN>5
    puts "FAN > 5";
elsif FAN>3
    puts "3 < FAN < 5";
else
    puts "FAN < 3";
end

#encoding:gbk
FAN = 10;
if FAN>5
puts "FAN > 5";
elsif FAN>3
puts "3 < FAN < 5";
else
puts "FAN < 3";
end

2. unless语句

unless语句和if相反，如果条件不成立则执行

[ruby]
#encoding:gbk
FAN = 10;
if FAN>5
    puts "FAN > 5";
elsif FAN>3
    puts "3 < FAN < 5";
else
    puts "FAN < 3";
end

puts "*******************************";

puts "unless test" unless FAN > 20;

#encoding:gbk
FAN = 10;
if FAN>5
puts "FAN > 5";
elsif FAN>3
puts "3 < FAN < 5";
else
puts "FAN < 3";
end

puts "*******************************";

puts "unless test" unless FAN > 20;

3. case语句
[ruby]
#encoding:gbk
FAN = 10;
if FAN>5
    puts "FAN > 5";
elsif FAN>3
    puts "3 < FAN < 5";
else
    puts "FAN < 3";
end

puts "*******************************";

puts "unless test" unless FAN > 20;

puts "*******************************";

NUM = 6;
case NUM
    when 5
        puts "5";
    when 6
        puts "6";
end

#encoding:gbk
FAN = 10;
if FAN>5
puts "FAN > 5";
elsif FAN>3
puts "3 < FAN < 5";
else
puts "FAN < 3";
end

puts "*******************************";

puts "unless test" unless FAN > 20;

puts "*******************************";

NUM = 6;
case NUM
when 5
puts "5";
when 6
puts "6";
end
case语句中的when 还可以是一个范围。

4. while循环
[ruby]
#encoding:gbk
FAN = 10;
a = 1;

while a < FAN do
    puts a;
    a=a+1;
end

#encoding:gbk
FAN = 10;
a = 1;

while a < FAN do
puts a;
a=a+1;
end
Ruby中不支持++运算符

5. for循环
[ruby]
#encoding:gbk
FAN = 10;
a = 1;

while a < FAN do
    puts a;
    a=a+1;
end

FOODS = ["巧克力","面包","蛋糕","牛奶"];
for f in FOODS do
    puts f;
end

#encoding:gbk
FAN = 10;
a = 1;

while a < FAN do
puts a;
a=a+1;
end

FOODS = ["巧克力","面包","蛋糕","牛奶"];
for f in FOODS do
puts f;
end

还可以遍历Hash对象

[ruby]
#encoding:gbk
FAN = 10;
a = 1;

while a < FAN do
    puts a;
    a=a+1;
end

FOODS = ["巧克力","面包","蛋糕","牛奶"];
for f in FOODS do
    puts f;
end

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

for name,age in Stus do
    puts name, age;
end

#encoding:gbk
FAN = 10;
a = 1;

while a < FAN do
puts a;
a=a+1;
end

FOODS = ["巧克力","面包","蛋糕","牛奶"];
for f in FOODS do
puts f;
end

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

for name,age in Stus do
puts name, age;
end

6. 迭代器

使用数组或者Hash对象自带的迭代器

[ruby]
#encoding:gbk
FAN = 10;
a = 1;

FOODS = ["巧克力","面包","蛋糕","牛奶"];
FOODS.each do |f|
    puts f;
end

Stus = {"小王"=>"29","小李"=>"23","小宋"=>"25"};
Stus.each do |name,age|
    puts name,age;
end

#encoding:gbk
FAN = 10;
a = 1;

FOODS = ["巧克力","面包","蛋糕","牛奶"];
FOODS.each do |f|
puts f;
end

Stus = {"小王"=>"29","小李"=>"23","小宋"=>"25"};
Stus.each do |name,age|
puts name,age;
end

7. 循环控制

[ruby]
loop{
    puts "(((((((((((((((())))))))))))))))))))":
    i=i+1;
    if(i>3)
        break;
    end
}

loop{
    puts "(((((((((((((((())))))))))))))))))))":
    i=i+1;
    if(i>3)
        break;
    end
}

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