給定一個字串，可能包含空格、字母等轉化為數字，或者逆序輸出數字

    下面是具體實現：

#!usr/bin/env python
#encoding:utf-8


'''
__Author__:沂水寒城
功能：將字串轉化為數字
'''

def trans_str2_num(one_str):
    '''
    '''
    sigmod=1
    one_str=one_str.strip()
    if not one_str:
        return 0
    if one_str[0]=='-':
        sigmod=-1
        one_str=one_str[1:]
    elif one_str[0]=='+':
        one_str=one_str[1:]
    else:
        pass
    one_str_list=list(one_str)
    for i in range(len(one_str_list)):
        if not one_str_list[i].isdigit():
            one_str_list=one_str_list[:i]
            break 
    res=0
    #想逆序輸出的話可以使用
    # for one in one_str_list[::-1]:
    for one in one_str_list:
        res+=ord(one)-ord('0')
        res*=10
    res/=10
    res*=sigmod 
    if res>2147483647:
        return 2147483647
    elif res<-2147483647:
        return -2147483647
    else:
        return res 


if __name__ == '__main__':
    one_str_list=['',' ','-123j442','2389083','hjsdhvj','21474836479','-21474836479']
    for one_str in one_str_list:
        print one_str+'---->'+str(trans_str2_num(one_str))
 

結果如下：

---->0
 ---->0
-123j442---->-123
2389083---->2389083
hjsdhvj---->0
21474836479---->2147483647
-21474836479---->-2147483647
[Finished in 0.7s]