python006（求1-2+3-4+5.....99的所有数的和）

 1 # 求1-2+3-4+5.....99的所有数的和（含等式）
 2 s = ""
 3 
 4 sum = 0
 5 start = 1
 6 
 7 while start < 100:
 8     temp = start % 2
 9     if temp == 1:
10         if start == 1:
11             s = str(start)
12         else:
13             s = s + "+" + str(start)
14         sum = sum + start
15     else:
16         s = s + "-" + str(start)
17         sum = sum - start
18     start += 1
19     
20 print(s)
21 print(start)
22 
23 
24 
25 # 求1-2+3-4+5.....99的所有数的和（不含等式）
26 sum = 0
27 start = 1
28 
29 while start < 100:
30     temp = start % 2
31     if temp == 1:
32         sum = sum + start
33     else:
34         sum = sum - start
35     start += 1
36     
37 print(sum)
38 print(start)