课后练习：求1-100的所有数的和

（1）while循环

#!/usr/bin/env python
#-*- coding:utf-8 -*-
n = 1
sum = 0
while n < 101:
    print(n)
    sum = sum + n
    n = n + 1
print(sum)

（2）for循环

#!/usr/bin/env python
#-*- coding:utf-8 -*-
sum = 0
for a in range(1,101,1):
    sum = sum + a
print(sum)

#!/usr/bin/env python
#-*- coding:utf-8 -*-
sum = 0
for a in range(1,101,1):
    sum = sum + a
    print(a)
print(sum)

执行结果：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
5050

Process finished with exit code 0