返回值
函数并非总是直接显示输出，相反，它可以处理一些数据，并返回一个或一组值。函数的返回值被称为返回值。
1. 简单的返回值
def get_formatted_name(first_name, last_name):
full_name = first_name + ' ' + last_name
return full_name.title()
musician = get_formatted_name('jimi', 'hendrix')
print(musician)
调用返回值的函数时，需要提供一个变量存储返回的值。
2. 让实参变成可选的
def get_formatted_name(first_name, middle_name, last_name):
full_name = first_name + ' ' + middle_name + ' ' + last_name
return full_name.title()
musician = get_formatted_name('john', 'lee', 'hooker')
print(musician)
然而并非每个人都有中间名，怎样让中间名变成可选呢？
def get_formatted_name(first_name, last_name, middle_name=' '):
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('john', 'hooker', 'lee')
print(musician)
musician = get_formatted_name('jimi', 'hendrix')
print(musician)
给形参中间名一个空字符为默认值，将其移动至形参列表的末尾；调用函数时确保实参中间名方最后。
相关推荐：《Python视频教程》
3. 返回字典
def build_person(first_name, last_name):
person = {'first': first_name, 'last': last_name}
return person
musician = build_person('jimi', 'hendrix')
print(musician)
扩展函数，使其接受可选值
def build_person(first_name, last_name, age=' '):
person = {'first': first_name, 'last': last_name}
if age:
person['age'] = age
return person
musician = build_person('jimi', 'hendrix', age=27)
print(musician)
4. 结合使用函数和while循环
def get_formatted_name(first_name, last_name):
full_name = first_name + ' ' + last_name
return full_name.title()
while True:
print("nPlease tell me your name:")
f_name = input("First name: ")
l_name = input("Last name: ")
formatted_name = get_formatted_name(f_name, l_name)
print("nHello, " + formatted_name + "!")
循环调用定义的函数，say hello everyone!!! 该在什么地方提供推出呢？
def get_formatted_name(first_name, last_name):
full_name = first_name + ' ' + last_name
return full_name.title()
while True:
print("nPlease tell me your name:")
print("(enter 'q' at any time to quit)")
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("nHello, " + formatted_name + "!")
每次提示用户输入时均可推出。
