我的名字是Philippian

替换 复制 改变

替换replace 方法

str="hehe"
puts "替换前是"+str
str.replace("呵呵哒")
puts "替换后是"+str

替换前是hehe
替换后是呵呵哒

复制 dup clone 方法
dup只复制内容，clone 复制其特殊方法，taint，freeze等信息

str="Philippian"
puts str.dup
puts str.clone

Philippian
Philippian

改变 有多种方法，如下：

获取

str="Philippian"
puts "第二个字符为"+str[1]
puts "二到六字符为"+str[1..5]
puts "第二个字符的ASCII值是"+str[1].ord.to_s
puts "从第5个字符开始往后的三个字符"+str[4,3]

第二个字符为h
二到六字符为hilip
第二个字符的ASCII值是104
从第5个字符开始往后的三个字符ipp

比较

a=String.new
a="good"
b=a #a b指向同一内存
c="good"  #c与ab不同
puts a==b #ab内容相同
puts a.eql?b #ab内容相同
puts a==c #ac内容相同
puts a.eql?c #ac内容相同
puts a.equal?c #ac不是同一对象
puts a.equal?b #ab是同一对象

true
true
true
true
false
true

比较大小
使用<=> 符号比较字符串大小，表达式的结果和含义如下：

6.3 Hash

创建Hash对象。形式为 key=>value

student={
    "num"=>"11001101110"
    "name"=>"Philippian"
    "sex"=>"m"
    "major"=>"computer science"
}

或者：

student=Hash.new
student["num"]="11001101110"
student["name"]="Philippian"

常用方法：

迭代器

6.4 数组

两种方式创建数组：
1

stu_name=["小明","小强","小刚","小红","小芳"]

2

stu_name=Array.new
stu_name[0]="小明"
stu_name[1]="小强"

取元素：

stu_name=["小明","小强","小刚","小红","小芳"]
puts stu_name[-2] #倒数第二个
puts stu_name[2] #正数第三个

小红
小刚

增删元素

组合与截取

stu_name1=["小明","小强","小刚"]
stu_name2=["小红","小芳"]
stu_name1.concat(stu_name2) #将第二个数组加到第一个里面
puts stu_name1
puts "------"
puts stu_name1[2..4] #截取第三个到第五个

小明
小强
小刚
小红
小芳
——
小刚
小红
小芳

7. 类,对象,方法

7.1 类

注意：
1. 类的定义
2. 表达式的执行
3. 方法定义
4. self 关键字
5. 创建对象
6. 对象调用方法

class Man #类的名字首字母大写
    puts "I am a man" #表达式直接执行
    puts self.class #self关键字指自己，此时self为类
    def sayName name #定义方法，方法名后面是参数
        puts "my name is "+name.to_s
        puts self.class 
        #self关键字指自己，此时为Man创建的对象
    end
end
stu1=Man.new #创建对象
stu1.sayName("Philippian") #调用方法

I am a man
Class
my name is Philippian
Man

7.1.1 追加类

名字相同的类自动合并

class Student
    def sayName name
        puts "my name is "+name
    end
end
class Student
    def sayAge age
        puts "my age is "+age.to_s
    end
end
Phi=Student.new
Phi.sayAge 18
Phi.sayName "Philippian"

my age is 18
my name is Philippian

7.1.2 嵌套类

也叫内部类，使用内部类用::

class Student
    def sayName name
        puts "My name is "+name
    end
    class Homework
        def doHomework
            puts "I did my Homework"
        end
    end
end
he=Student.new
he.sayName "Philippian"
math=Student::Homework.new
math.doHomework

My name is Philippian
I did my Homework

7.1.3 特殊类

专门为某个对象添加的类

class Student
    def sayName name
        puts "My name is "+name
    end
end
he=Student.new
he.sayName "Philippian"
class <<he #特殊类
    def singSong song_name
        puts "I sang a song, its name is "+song_name
    end
end
he.singSong "我有一只小毛驴"

My name is Philippian
I sang a song, its name is 我有一只小毛驴

7.2 方法

7.2.1 默认参数

class Student
    def saySomething sentences="I am a Student" #设置默认参数的值
        puts sentences
    end
end
he=Student.new
he.saySomething #没有参数时候
he.saySomething "I want to have a holiday!" #有的参数值时候

I am a Student
I want to have a holiday!

7.2.2 返回值

class Xiaoming
    def sayName
        "Xiaoming"
    end
    def sayAge
        return 19
    end
end
xiaoming=Xiaoming.new
puts xiaoming.sayName
puts xiaoming.sayAge.to_s

Xiaoming
19

7.2.3 特殊方法

class Student
    def sayName name
        puts "My name is "+name
    end
end
he=Student.new
he.sayName "Philippian"
def he.sayAge age #特殊方法
    puts "My age is "+age.to_s
end
he.sayAge 18

Xiaoming
19

7.2.4 类方法

class Student
    def Student.sayClass
        puts self.class
    end
end
Student.sayClass

Class

7.2.5 构造方法

构造方法名字为initialize ，当调用new方法创建对象的时候，自动调用initialize 初始化

class Student
    def initialize name,age
        @name=name
        @age=age
    end
    def show
        puts "My name is #{@name}, My age is #{@age}"
    end
end
he=Student.new "Philippian",19
he.show

My name is Philippian, My age is 19

7.3 变量与属性

7.3.1 实例变量

实例变量用于在类内部共享数据。 变量名以@ 开头。
可以在以下几个地方声明实例变量：

• 顶层和顶层方法，
• 类和类方法，
• 模块和模块方法

7.3.2 类变量

类变量用于在各个类之间共享数据。允许定义位置与实例变量相同
类变量以@@ 开头

7.3.3 属性

属性设置器和读取器

class Student
    @university
    def setUniversity=(val)
        @university=val
    end
    def university
        @university
    end
end
he=Student.new
he.setUniversity="SYSU"
puts he.university

SYSU

声明属性的标识符

7.4 类的继承

class Animal
    def eat
        puts "I can eat"
    end
    def breathe
        puts "I can breathe"
    end
end
class Dog<Animal #继承
    def run #Dog类自己的方法
        puts "I am a dog, I can run"
    end
    def eat #重写父类的方法
        puts "I am a dog, I like eating bone"
    end
end
wangwang=Dog.new
wangwang.eat
wangwang.breathe
wangwang.run

I am a dog, I like eating bone
I can breathe
I am a dog, I can run

访问父类构造方法

class Student
    def initialize (name, age)
        @name=name
        @age=age
    end
    def saySomething
        puts "I can say something"
    end
end
class UniversityStudent<Student
    def initialize stu_num
        @stu_num=stu_num
        super("Philippian", 18) #super关键字访问父类构造方法
    end
    def show
        puts "My name is #{@name}, my age is#{@age}, \nmy student numbe is #{@stu_num}"
    end
end
he=UniversityStudent.new 1111111111
he.saySomething
he.show

I can say something
My name is Philippian, my age is18,
my student numbe is 1111111111

7.5 作用域

两种方法定义访问级别
1. 使用无参数的方法

class Animal
    def eat #默认public
        puts "I can eat"
    end

    public #定义为公有方法
    def drink
        puts "I can drink"
    end

    private #定义为私有方法
    def breathe 
        puts "I can breathe"
    end

    protected #定义为保护方法
    def run
        puts "I can run"
    end
end

‘2. 使用参数指定成员

class Animal
    def eat
        puts "I can eat"
    end

    def run
        puts "I can run"
    end

    def breathe
        puts "I can breathe"
    end

    private(:eat) #定义为私有方法
    protected(:breathe,:run)#定义为保护方法
end

7.6 代码块

用{ } 或者 do...end 创建代码块，用yield 传入代码块

def saySomething
    puts "This is the 1st in method"
    yield
    puts "This is the 2nd in method"
end
saySomething do
    puts "This is in a block"
end

saySomething{
    puts "This is in a block too"
}

This is the 1st in method
This is in a block
This is the 2nd in method
This is the 1st in method
This is in a block too
This is the 2nd in method

此外，代码块还可以有参数、返回值等。