Python中的函数

不念不忘少年蓝@ 2021-07-25 19:15 517阅读 0赞

**目录**

一、基本用法

二、函数返回值

三、传递任意参数

--------------------

# 一、基本用法 #

*  定义函数
 *  声明参数
 *  参数默认值

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70][]

# 定义函数
    def hello():
        print("hello world.")
    
    hello()
    print("-----------------------")
    
    # 声明参数
    def hello2(name):
        print("hello,", name)
    
    hello2("lijiang")
    print("-----------------------")
    
    # 参数默认值
    def hello3(name="lijiang"):
        print("哈喽，", name)
    
    hello3()
    hello3("张三")

# 二、函数返回值 #

*  返回数值
 *  返回字符
 *  返回字典

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 1][]

# 返回数值
    def add(x, y):
        return x + y
    
    print(add(10, 20))
    print("-------------------")
    
    # 返回字符
    def user(username, password):
        str = ""
        str += "username=" + username + ";"
        str += "password=" + password + ";"
        return str
    
    print(user("lijiang", "123"))
    print("-------------------")
    
    # 返回字典
    def user(username, password):
        return {
            "username": username,
            "password": password,
        }
    
    db = user("lijiang", 123)
    print(db)
    print(db["username"])
    print(db["password"])

# 三、传递任意参数 #

*  传递任意参数
 *  传递关键字参数

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 2][]

# 传递任意参数
    def add(*num):
        result = 0
        for val in num:
            result += val
        return result
    
    print(add(1, 2, 3))
    print(add(1, 2, 3, 4, 5))
    
    print("-----------------")
    # 传递关键字参数
    def sendmail(**data):
        for key, val in data.items():
            print(key, ":", val)
    
    sendmail(username="lijiang",  password=123)

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