学习Python （5）生成随机密码

#coding=utf-8
#随机密码
import random,string

def getPsd(len):
	"""
	#获取含有数字、字母、特殊字符的组合
	'''0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~ \t\n\r\x0b\x0c'''
	a = [random.choice(string.printable) for i in range(len)] 
	#获取纯数字密码
	'''0123456789'''
	b= [random.choice(string.digits) for i in range(len)] 
	#获取纯字母含大小写
	''' abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'''
	c= [random.choice(string.ascii_letters) for i in range(len)] 
	"""
	
	selectChar = raw_input("a:获取含有数字、字母、特殊字符的组合\nb:获取纯数字密码\nc:获取纯字母含大小写\nd:获取数字和字母组合\n三次选中密码机会：" )
	if selectChar == 'a':
		psd = "".join([random.choice(string.printable) for i in range(len)] )
		return psd
	elif selectChar == 'b':	
		psd = "".join([random.choice(string.digits) for i in range(len)])
		return psd
	elif selectChar == 'c':	
		psd = "".join([random.choice(string.ascii_letters) for i in range(len)] )
		return psd	
	elif selectChar == 'd':	
		psd = "".join([random.choice(string.ascii_letters + string.digits) for i in range(len)] )
		return psd		
if __name__ == '__main__':
	for i in range(3):
		print getPsd(12)