Python中相关知识点须知

python中*args **kw到底是什么意思

*args是非关键字参数，用于元组，**kw是关键字参数，用于字典 举例：

1.*args

def tupleArgs(arg1, arg2= ‘B’, *arg3):
print(‘arg 1:%s ‘ % arg1)
print(‘arg 2:%s ‘ % arg2)
for eachArgNum in range(len(arg3)):
print(‘the %d in arg 3 :%s ‘ % (eachArgNum,arg3[eachArgNum]))
if __name__ == ‘__main__‘:
tupleArgs(‘A’)

#   arg 1:A 
#   arg 2:B 
tupleArgs('23','C')
#   arg 1:23 
#   arg 2:C
tupleArgs('12','A','GF','L')
#   arg 1:12 
#   arg 2:A 
#   the 0 in arg 3 :GF 
#   the 1 in arg 3 :L 

**kw

def dictArgs(kw1, kw2= 'B', **kw3):
print('kw 1:%s ' % kw1)
print('kw 2:%s ' % kw2)
for eachKw in kw3:
    print('the %s ---->:%s ' % (eachKw,kw3\[eachKw\]))

if __name__ == ‘__main__‘:
dictArgs(‘A’)

#   kw 1:A 
#   kw 2:B 
dictArgs('23','C')
#   kw 1:23 
#   kw 2:C 
dictArgs('12','A', c = 'C',d = '12121212')
#   kw 1:12 
#   kw 2:A 
#   the d ---->:12121212 
#   the c ---->:C 
dictArgs('kw',c = 'C',d = '12121212',kw = 'KW')
#   kw 1:kw 
#   kw 2:B 
#   the kw ---->:KW 
#   the d ---->:12121212 
#   the c ---->:C

其它意义

1. 两个乘号就是乘方，比如24,结果就是2的4次方，结果是16

2. 一个乘号，如果操作数是两个数字，就是这两个数字相乘，如24,结果为8

3. 如果是字符串、列表、元组与一个整数N相乘，返回一个其所有元素重复N次的同类型对象，
比如”str”3将返回字符串”strstrstr”