num = 10
if num < 9:
    print('true')
else:
    print('false')
 
# 三元简写   
print( 'true' if num < 9 else 'false')  # 'false'

a, b = 2, 3
 
# 传统思维
temp = a 
a = b 
b = temp
 
# 简写
a, b = b, a # 3, 2

a = {'name': 'abc', 'age': 19}
b = {'job': 'student', 'gender': 'male'}
c = {'name': 'ABC', 'age': 20}
print({**a, **b})   #{'name': 'abc', 'age': 19, 'job': 'student', 'gender': 'male'}
print({**a, **c})   #{'name': 'ABC', 'age': 20}   ## danger

a = {'name': 'abc', 'age': 19}
b = {'job': 'student', 'gender': 'male'}
c = {'name': 'ABC', 'age': 20}
 
d = {}
d.update(a)
d.update(c)
print(d)    #{'name': 'abc', 'age': 19, 'job': 'student', 'gender': 'male'}

a = {'name': 'abc', 'age': 19}
b = {'job': 'student', 'gender': 'male'}
c = {'name': 'ABC', 'age': 20}
 
d = {}
for k,v in a.items():
    d[k] = v
 
for k,v in c.items():
    d[k] = v
 
print(d)        # {'name': 'ABC', 'age': 20}  ## danger

# 低版本适用
d = dict(a.items() + b.items())

url = 'https://zhibo.sina.com.cn/api/zhibo/feed'
_params = {
  "page": 1,
  "page_size": 100,
  "zhibo_id": 152,
  "tag_id": 0,
  "dire": 'f',
  "dpc": 1,
  "type": 0
}

res = ''
for k in _params:
    res += '&' + str(k) + '=' + str(_params[k])
 
res = res[1:]   # 去掉首位多余的一个  &
url = url + '?' + res[1:]   
print(url)  # https://zhibo.sina.com.cn/api/zhibo/feed?age=1&page_size=100&zhibo_id=152&tag_id=0&dire=f&dpc=1&type=0

res = ''
for k in _params:
    res += '&%s=%s' % (str(k), _params[k])
 
url = 's%?s%' % (url, res[1:])  
print(url)  # https://zhibo.sina.com.cn/api/zhibo/feed?age=1&page_size=100&zhibo_id=152&tag_id=0&dire=f&dpc=1&type=0

res = ''
for k in _params:
    res += '&{}={}'.format(str(k), _params[k])
 
url = '{}?{}'.format(url, res[1:])
print(url)  # https://zhibo.sina.com.cn/api/zhibo/feed?age=1&page_size=100&zhibo_id=152&tag_id=0&dire=f&dpc=1&type=0

res = ''
for k in _params:
    res += f'&{k}={_params[k]}'
 
res = res[1:]   # 去掉首位多余的一个  &
url = f'{url}?{res[1:]}' 
print(url)  # https://zhibo.sina.com.cn/api/zhibo/feed?age=1&page_size=100&zhibo_id=152&tag_id=0&dire=f&dpc=1&type=0

fruit  = ['apple', 'pear', 'banana', 'cheery']
 
for i in range(len(fruit)):
   fruit[i] = fruit[i].upper()
 
print(fruit)    #['APPLE', 'PEAR', 'BANANA', 'CHEERY']

fruit  = ['apple', 'pear', 'banana', 'cheery']
fruit = [x.upper() for x in fruit] 
print(fruit)    #['APPLE', 'PEAR', 'BANANA', 'CHEERY']
 
# 扩展 #只大写首字母
fruit = [x[:1].upper() + x[1:] for x in fruit]  
print(fruit)    #['Apple', 'Pear', 'Banana', 'Cheery']

name = 'ABC 123'
str_list = name.split()
print(str_list[0])  #'ABC'
print(str_list[1])  #'123'
 
a, b = name.split()
print(a)  #'ABC'
print(b)  #'123'

fruit  = ['apple', 'pear', 'banana', 'cheery']
a = []
b = []
 
for index, value in enumerate(fruit):
    a.append(index)
    b.append(value)
 
print(a)    #[0, 1, 2, 3]
print(b)    #['apple', 'pear', 'banana', 'cheery']

fruit  = ['apple', 'pear', 'banana', 'cheery']
a = []
b = []
# 反序 reversed(fruit)
for index, value in enumerate(sorted(fruit)):
    a.append(index)
    b.append(value)
 
print(a)    #[0, 1, 2, 3]
print(b)    #['apple', 'banana', 'cheery', 'pear']   按字母顺序输出sort()会改变原数组，sorted()会生成新数组

def fib(n):
    a = 0
    b = 1
    nums = []
    while a < n:
        nums.append(a)
        a, b = b , a + b
    return nums
 
for i in fib(30):
    print(i)
# 满足条件的元素全部压入nums列表之后才执行for循环
 
==============yield==============
def fib(n):
    a = 0
    b = 1
    while a < n:
        yield a     # 不用等全部列表元素循环压入结束，而是立马将 a 抛出去，常用于耗时操作
        a, b = b , a + b
 
for i in fib(30):
    print(i)

file = open('./test.json', 'r')
...
file.close()
 
## 使用with语句就省去了close()
with open('./test.json', 'w', encoding = 'utf8') as json_file:
    json.dump(res_data, json_file, ensure_ascii = False)
 
## 想要处理err时候，用 try...except
try:
    with open('./test.json', 'w', encoding = 'utf8') as json_file:
        json.dump(res_data, json_file, ensure_ascii = False)
except ValueError as err:
    print(err)