1 """
2 python程序的流程
3 """
4 # ------------- 分支结构----------------
5 # if else
6 import math
7
8 x = -37
9 if x < 0:
10 y = math.fabs(x)
11 else:
12 y = math.sqrt(x)
13 print("计算的结果是：", y)
14
15 # if...elif...else
16 # month = eval(input("请输入你选择的月份：")) # eval() 函数用来执行一个字符串表达式，并返回表达式的值
17 month = 12
18 days = 0
19
20 if (month == 1 or month == 3 or month == 5 or month == 7
21 or month == 8 or month == 10 or month == 12):
22 days = 31
23 elif month == 4 or month == 6 or month == 9 or month == 11:
24 days = 30
25 else:
26 days = 28
27 print("{}月份的天数为{}".format(month, days))
28
29 # 分支嵌套
30 flag = 1
31 books = 8
32 price = 234
33 Acp = 0
34
35 if flag == 1:
36 if books >= 5:
37 Acp = price * 0.75 * books
38 else:
39 Acp = price * 0.85 * books
40 else:
41 if books >= 5:
42 Acp = price * 0.85 * books
43 else:
44 Acp = price * 0.95 * books
45 print("你的实际付款金额是：", Acp)
46
47 # ------------循环结构---------------
48
49 # 遍历循环：for
50 '''
51 for <var> in <seq>:
52 <statements>
53 var是一个变量
54 seq是一个序列，可以是字符串、列表、文件或range()函数
55
56 range()函数
57 range(start,stop,[,step])
58 start：默认从0开始
59 stop：默认到stop结束，但不包括stop
60 step：默认为1
61 '''
62 # 计算1-100中能被3整除数之和
63 s = 0
64 for i in range(1, 101, 1):
65 if i % 3 == 0:
66 s += i
67 # print(i)
68 print(s)
69
70
71 # 计算 1！+2！+...+5!
72 def factorial(n):
73 t = 1
74 for v in range(1, n + 1):
75 t = t * v
76 return t
77
78
79 k = 6
80 sum1 = 0
81 for j in range(1, k):
82 sum1 += factorial(j)
83 print("1！+2！+...+5!=", sum1)
84
85 # 条件循环语句while
86 """
87 while <boolCondition>
88 <statements>
89 """
90
91 lst = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
92 head = 0
93 tail = len(lst) - 1
94 while head < len(lst) / 2: # TypeError: object of type 'type' has no len()/报错，需修改
95 lst[head], lst[tail] = lst[tail], lst[head] # 头尾互换?
96 """
97 也可以用下面语句来进行头尾互换
98 temp = list[head]
99 lst[head] = list[tail]
100 lst[tail] = temp
101 """
102 head += 1
103 tail -= 1
104
105 for item in lst:
106 print(item, end=' ')
107
108 # 用for循环改写
109 lst = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
110 head = 0
111 tail = len(lst) - 1
112 for head in range(0, int(len(lst) / 2)): # 因为range（）函数的参数必须是整数，所以用int（）函数进行了转换
113 lst[head], lst[tail] = lst[tail], lst[head] # 头尾互换?
114 """
115 也可以用下面语句来进行头尾互换
116 temp = list[head]
117 lst[head] = list[tail]
118 lst[tail] = temp
119 """
120 head += 1
121 tail -= 1
122
123 for item in lst:
124 print(item, end=' ')
125 print()
126
127 # ------------跳转语句----------------
128 """
129 break语句的作用是从循环体内跳出，及结束循环
130 """
131 a = 99
132 i = a // 2
133 while i > 0:
134 if a % i == 0:
135 break
136 i -= 1
137 print(a, "的最大真约数：", i)
138
139 """
140 continue语句必须用于循环结构中，它的作用是终止当前的这一轮循环，跳过本轮剩余的语句，直接进入下一循环
141 """
142 s = [-1, -2, -3, -4, 5, 6, 7, 8, 9]
143 for i in range(9):
144 if s[i] < 0:
145 continue
146 print("{}是正数".format(s[i]))
147
148 # 打印金字塔
149 # n = eval(input("请输入打印的行数"))
150 n = 5
151 for i in range(1, n + 1):
152 print(' ' * (n - i) + '*' * (2 * i - 1)) # 感觉这个print函数都够学的了
