【转】局部变量和全局变量---------------【答不对，你还敢说你精通、熟悉python？】

转载：https://www.cnblogs.com/uncleyong/p/11230413.html    局部变量和全局变量

#== == == == == == == == 第一部分 == == == == == == == == ==
 2 res = None
 3 def calc(a, b):
 4     res = a + b
 5 calc(1, 2)
 6 print(res)
 7 #上面代码结果是：None

res = None
def calc(a, b):
    res = 0
    res = a + b
calc(1, 2)
print(res)
#上面代码结果是：None

res = None
def calc(a, b):
    global res
    res = a + b
calc(1, 2)
print(res)
#上面代码结果是：3

res2 = None
def calc(a, b):
    global res
    res = a + b
calc(1, 2)
print(res)
#上面代码结果是：3　

# res = None
# def calc(a, b):
#     res = a + b
#     global res
# calc(1, 2)
# print(res)
#上面代码结果是：运行报错    name 'res' is assigned to before global declaration

res = None
def calc(a, b):
    global res
    res = 0
    res = a + b
calc(1, 2)
print(res)
#上面代码结果是：3

# res = None
# def calc(a, b):
#     res = 0
#     global res
#     res = a + b
# calc(1, 2)
# print(res)
#上面代码结果是：运行报错

# res = None
# def calc(a, b):
#     res = 0
#     res = a + b
#     global res
# calc(1, 2)
# print(res)
#上面代码结果是：运行报错

money = 0
def tom():
    global money
    money = 180
    print(id(money))
def jack():
    global money1
    money1=150
    money = money1 - 50
    print(id(money))
tom()
jack()
print('jack消费后剩余%s' % money)
#上面代码结果是： 100

def tom():
    global money
    money = 100
def jack():
    global money
    money = money - 50
tom()
jack()
print('jack消费后剩余%s' % money)
#上面代码结果是：50　（不是-50） 问题1、这里重复定义全局变量money后，它还保留之前的值100  可以这样理解吗 ？

 

 

 

# == == == == == == == == 第二部分 == == == == == == == == ==
  2 d = {}
  3 def test():
  4     d['url'] = 'https://www.cnblogs.com/uncleyong/p/10530261.html'
  5 def test2():
  6     d['url'] = 'https://www.cnblogs.com/uncleyong/'
  7 test()
  8 test2()
  9 print(d)
 10 # 上面代码结果是： {'url': 'https://www.cnblogs.com/uncleyong/'}

def test():
    d = {}
    d['url'] = 'https://www.cnblogs.com/uncleyong/p/10530261.html'
def test2():
    d = {}
    d['url'] = 'https://www.cnblogs.com/uncleyong/'
test()
test2()
print(d)
# 上面代码结果是： {'url': 'https://www.cnblogs.com/uncleyong/'}（不会报错）

def test():
    d = {}
    d['url'] = 'https://www.cnblogs.com/uncleyong/p/10530261.html'
def test2():
    global d
    d = {}
    d['url'] = 'https://www.cnblogs.com/uncleyong/'
test()
test2()
print(d)
# 上面代码结果是：{'url': 'https://www.cnblogs.com/uncleyong/'}

info = {'age': 18, 'url': 'https://www.cnblogs.com/uncleyong/p/10530261.html'}
def test():
    global info
    info = {}
    info['name'] = 'qzcsbj'
test()
print(info)
# 上面代码结果是：{'name': 'qzcsbj'}

info = {'age': 18, 'url': 'https://www.cnblogs.com/uncleyong/p/10530261.html'}
 45 def test():
 46     info = {}
 47     info['name'] = 'qzcsbj'
 48 test()
 49 print(info)
 50 # 上面代码结果是：{'age': 18, 'url': 'https://www.cnblogs.com/uncleyong/p/10530261.html'}
===============

info = {'age': 18, 'url': 'https://www.cnblogs.com/uncleyong/p/10530261.html'}
def test():
    info = {}
    info['name'] = 'qzcsbj'
    print(info) #打印结果 {'name': 'qzcsbj'}，使用当前局部变量的值，不是全局变量的值
test()
print(info)
# 上面代码结果是：{'age': 18, 'url': 'https://www.cnblogs.com/uncleyong/p/10530261.html'}

===============

info = {'age': 18, 'url': 'https://www.cnblogs.com/uncleyong/p/10530261.html'}
def test():
    info['age'] = info['age'] + 1
test()
print(info)
# 上面代码结果是：{'age': 19, 'url': 'https://www.cnblogs.com/uncleyong/p/10530261.html'}

s = 'https://www.cnblogs.com/uncleyong/p/10530261.html'
def test():
    s = 'test'
test()
print(s)
# 上面代码结果是：https://www.cnblogs.com/uncleyong/p/10530261.html

url = 'https://www.cnblogs.com/uncleyong/p/10530261.html'
def test():
    s = 'test'
test()
print(s)
# 上面代码结果是：https://www.cnblogs.com/uncleyong/p/10530261.html (没报错,取的第63行的s）

url = 'https://www.cnblogs.com/uncleyong/p/10530261.html'
def test():
    global s
    s = 'test'
test()
print(s)
# 上面代码结果是：test

s = 'https://www.cnblogs.com/uncleyong/p/10530261.html'
def test():
    global s
    s = 'test'
test()
print(s)
# 上面代码结果是：test

s = [1, 2, 3]
 90 def test():
 91     s[0] = 123
 92 test()
 93 print(s)
 94 # 上面代码结果是：[123, 2, 3]  数组也是全局变量？

s = [1, 2, 3]
def test():
    s = []
    s.append(123)
test()
print(s)
# 上面代码结果是：　[1, 2, 3]

s = [1, 2, 3]
def test():
106     global s
107     s[0] = 123
test()
print(s)
110 # 上面代码结果是：[123, 2, 3]  也算是全局变量再被定义时，仍保留了原来的值？

s = [1, 2, 3]
def test():
    global s
    s = []
    s.append(123)
test()
print(s)
# 上面代码结果是：[123]  把原来的值清空了

# s = (1, 2, 3)
# def test():
#     s[0] = 123
# test()
# print(s)
# 上面代码结果是：这句 s[0] = 123 报错  'tuple' object does not support item assignment  元组不能被修改

# s = (1, 2, 3)
# def test():
#     global s
#     s[0] = 123
131 #　　  print(s[0])  #打印结果是 1
# test()
# print(s)
# 上面代码结果是：这句 s[0] = 123 报错  'tuple' object does not support item assignment  元组不能被修改

s = {1, 2, 3}
def test():
    s.add(5)
test()
print(s)
# 上面代码结果是：{1, 2, 3, 5}

s = {1, 2, 3}
def test():
    global s
    s.add(5)
test()
print(s)
# 上面代码结果是：{1, 2, 3, 5}

s = {1, 2, 3}
def test():
    s = set() #这里是定义了一个局部变量，而不是将s={1,2,3}转换为元组
    s.add(5)  #这里是局部变量
test()
print(s)
# 上面代码结果是：{1, 2, 3} （需要注意）

s = {1, 2, 3}
def test():
    global s
    s = set()  
    s.add(5)
test()
print(s)
# 上面代码结果是：{5}

 字典 、 数组、集合、元组，都是全局变量？