Python函数常见几种return返回值类型

#返回一个数字：类型为int
def demo(a,b):
    c = a + b
    return c
print(demo(2,3))
print(type(demo(2,3)))
print()

#返回多个结果会自动生成一个tuple：类型为class 'tuple'
def demo1(a,b):
    c = a + b
    return a,b,c
print(demo(2,3))
print(type(demo(2,3)))

#返回值结果可以直接作为元组使用：
for i in demo1(2,3):
    print(i)
print()

#返回1个元组：类型为class 'tuple'
def demo2(a):
    return a
print(demo2((1,2)))
print(type((demo2((1,2)))))
print()

#返回1个字符串：类型为class 'str'
def demo3(a,b):
    c = a + b
    return c
print(demo3('aaa','bbb'))
print(type(demo3('aaa','bbb')))
print()

#传入1个列表：类型为class 'list'
def demo4(a):
    return a
j = demo4(list(range(5)))
print('j =',j)
print(type(j))

#返回结果可以直接作为列表使用：
sum = 0
for i in j:
    sum += i
print('sum = ',sum)
print()

#这里注意实参前加*的区别，加*是作为多个实参传入名为a的空元组，
#不加*的话是作为1个实参传入a形参，返回类型为：class 'tuple'
def demo4(*a):
    return a
k = demo4(list(range(5)))
print('k =',k)
print(type(k))
print(k[0][2:])
print()

#逆向传入列表，返回class 'tuple',可以作为元组直接使用
def demo4(*a):
    return a
k = list(range(5))
m = demo4(*k)
print('m =',m)
print(type(m))
for i in m:
    print(i, end = '')
print()
print()

#返回1个字典：类型为class 'dict'
def demo5(a):
    return a
dict_demo = {'a':1,'b':2}
d = demo5(dict_demo)
print('d:',d)
print('type of d:',type(d))
for i in d.values():
    print(i)
print()

#返回1个布尔类型：类型为class 'bool'
def demo6(a):
    return True
print(demo6(1))
print(type(demo6(1)))
print()

#返回None：类型为'NoneType'
def demo7(a):
    return None
print(demo6(1))
print(type(demo7(1)))