python实现判断一个字符串是否是合法IP地址

#!usr/bin/env python  
#encoding:utf-8  
  
''''' 
__Author__:沂水寒城 
功能：判断一个字符串是否是合法IP地址 
'''  
  
  
import re  
  
  
def judge_legal_ip(one_str):  
    ''''' 
    正则匹配方法 
    判断一个字符串是否是合法IP地址 
    '''  
    compile_ip=re.compile('^((25[0-5]|2[0-4]d|[01]?dd?).){3}(25[0-5]|2[0-4]d|[01]?dd?)$')    
    if compile_ip.match(one_str):    
        return True    
    else:    
        return False   
  
  
def judge_legal_ip2(one_str):  
    ''''' 
    简单的字符串判断 
    '''  
    if '.' not in one_str:  
        return False  
    elif one_str.count('.')!=3:  
        return False  
    else:  
        flag=True  
        one_list=one_str.split('.')  
        for one in one_list:  
            try:  
                one_num=int(one)  
                if one_num>=0 and one_num<=255:  
                    pass  
                else:  
                    flag=False  
            except:  
                flag=False  
        return flag  
                      
  
  
if __name__=='__main__':  
    ip_list=['','172.31.137.251','100.10.0.1000','1.1.1.1','12.23.13','aa.12.1.2','12345678','289043jdhjkbh']  
    for one_str in ip_list:  
        if judge_legal_ip(one_str):  #正则方法  
        #if judge_legal_ip2(one_str):  #字符串方法  
            print '{0} is a legal ip address!'.format(one_str)  
        else:  
            print '{0} is not a legal ip address!'.format(one_str)  


结果如下：

[html] view plain copy
 is not a legal ip address!  
172.31.137.251 is a legal ip address!  
100.10.0.1000 is not a legal ip address!  
1.1.1.1 is a legal ip address!  
12.23.13 is not a legal ip address!  
aa.12.1.2 is not a legal ip address!  
12345678 is not a legal ip address!  
289043jdhjkbh is not a legal ip address!