python入门-函数（一）

1定义函数并且调用  注释语句""" """

def greet_user():
    """显示简单的问候语"""
    print("hello!")

greet_user()

2定义带参数的函数

def greet_user(username):
    """显示简单的问候语"""
    print("hello" + username.title() + "!")

greet_user('baker')

3 形参和实参

def describe_pet(animal_type,pet_name):
    """显示宠物信息"""
    print("
 I have a " + animal_type +".")
    print("My " + animal_type + "'s name is " + pet_name.title() + ".")

describe_pet('hamster','harry')
describe_pet('dog','willie')

describe_pet(pet_name='willie',animal_type='dog')

4  有返回值的函数

def get_formatted_name(first_name,last_name):
    """返回整洁的名字"""
    full_name = first_name + " "+last_name
    return full_name.title()

musician = get_formatted_name("jimi" , "baker")

print(musician)

5  参数可以为空的函数

def get_formatted_name(first_name,last_name,middle_name=''):
    """返回整洁的名字"""
    if middle_name:
        full_name = first_name + " " + middle_name + " "+ last_name
    else:
        full_name = first_name + " " + last_name

    return full_name.title()

musician = get_formatted_name('jimi','hendrix')
print(musician)

6 返回值可以是字典  或者列表  

def build_person(first_name,last_name):
    """返回一个字典，其中包含一个人的信息"""
    person = {'first':first_name, 'last':last_name}
    return person

musician = build_person('jimi','hendrix')
print(musician)

7 返回是字典，有额外的信息

def build_person(first_name,last_name,age=''):
    """返回一个字典，其中包含一个人的信息"""
    person = {'first':first_name, 'last':last_name}
    if age:
        person['age'] = age

    return person

musician = build_person('jimi','hendrix',age=27)
print(musician)

8 函数和while循环

def get_formatted_name(first_name,last_name):
    """返回整洁的名字"""
    full_name = first_name + " " + last_name
    return full_name.title()

while True:
    print("
 Please tell me your name")
    f_name = input("First name:")
    if f_name == 'q':
        break
    l_name = input("Last name:")
    if l_name == 'q':
        break
    formatted_name = get_formatted_name(f_name,l_name)
    print("
hello," + formatted_name + "!")