将字符串转换成整数

 1 # -*- coding:utf-8 -*-
 2 class Solution:
 3     def StrToInt(self, s):
 4         # write code here
 5         if len(s)==0:
 6             return 0
 7         end = len(s)-1
 8         begin = -1
 9         temp = 1
10         int_s = 0
11         if s[0]==‘-‘ or s[0]==‘+‘:
12             begin = 0
13         for i in range(end,begin,-1):
14             if s[i]<‘0‘ or s[i]>‘9‘:
15                 return 0
16             int_s += temp*int(s[i])
17             temp = temp *10
18         if s[0]==‘-‘:
19             int_s = -int_s
20         return int_s

 1 # -*- coding:utf-8 -*-
 2 class Solution:
 3     # 大数问题
 4     def StrToInt(self, s):
 5         # write code here
 6         if len(s) == 0:
 7             return 0
 8         if len(s)==1 and (s[0]<‘0‘ or s[0]>‘9‘):
 9             return 0
10         end = len(s) - 1
11         begin = -1
12         int_s = [0]*len(s)
13         if s[0] == ‘-‘ or s[0] == ‘+‘:
14             begin = 0
15         for i in range(end, begin, -1): #range()函数，左闭右开 
16             if s[i]>=‘0‘ and s[i]<=‘9‘:
17                 int_s[i] = s[i]
18             else:
19                 return 0
20         if s[0] == ‘-‘:
21             int_s[0] = ‘-‘
22         if s[0]==‘+‘:
23             int_s = int_s[1:]
24         return int(‘‘.join(int_s))