#a = input()
#print(a)
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
print('''line\n
line2
line3''')
a = '124'
b = a;
a = '234';
print(a+" "+b);
#编码
chiness = '你好';
print(chiness.encode('utf-8'));
utf8 = b'\xe4\xbd\xa0\xe5\xa5\xbd';
print(utf8.decode('utf-8'));
print(len(utf8));
#列表
classmates = ['jone','lily','lucy','jack'];
print(classmates);
len(classmates);
classmates.append('lastone');
print("\n\nafter append");
print(classmates);
classmates.pop(3);
print('\n\nafter pop');
print(classmates);
#元组
classm = ('param1','param2','param3');
print(classm);
print(classm[0]);
#条件判断
age = 17;
if age >= 18:
print('you can do it');
elif age >= 16:
print('you can see it');
else:
print('you can not do it');
#循环
names = ['jack','bob','jame','lucy'];
index = 0;
for name in names:
print(name);
index = index + 1;
print(index);
sum = 100;
while sum > 1:
sum = sum - 1;
print('\n\nsum = ');
print(sum);
#字典
dict = {'age':25,'name':'jack'};
print(dict['name'],dict['age']);
dict.pop('age');
dict['sex'] = 1;
#set add remove
#函数 定义默认参数要牢记一点:默认参数必须指向不变对象!
def my_abs(x):
if x >= 0:
return x;
else:
return -x;
print(my_abs(-19));
import math
def move(x,y):
return x,y;
print(move(1,2));
Python的函数具有非常灵活的参数形态,既可以实现简单的调用,又可以传入非常复杂的参数。
默认参数一定要用不可变对象,如果是可变对象,程序运行时会有逻辑错误!
要注意定义可变参数和关键字参数的语法:
*args
是可变参数,args接收的是一个tuple;
**kw
是关键字参数,kw接收的是一个dict。
以及调用函数时如何传入可变参数和关键字参数的语法:
可变参数既可以直接传入:func(1, 2, 3)
,又可以先组装list或tuple,再通过*args
传入:func(*(1, 2, 3))
;
关键字参数既可以直接传入:func(a=1, b=2)
,又可以先组装dict,再通过**kw
传入:func(**{'a': 1, 'b': 2})
。
使用*args
和**kw
是Python的习惯写法,当然也可以用其他参数名,但最好使用习惯用法。
命名的关键字参数是为了限制调用者可以传入的参数名,同时可以提供默认值。
定义命名的关键字参数在没有可变参数的情况下不要忘了写分隔符*
,否则定义的将是位置参数。
def power(x):
return x * x;
def power(x,n = 2):
s = 1;
while n > 0:
s = s* x;
n = n-1;
return s;
print(power(3));
print(power(3,3));
def enroll(name,gender,age = 10,city = 'beijing'):
print('name:',name);
print('gender:',gender);
print('age:',age);
print('city:',city);
enroll('dsd','sdf');
enroll('ddd','sdf',city='nanjing');
def add_end(l=None):
if l is None:
l = [];
l.append('end');
return l;
print(add_end([]));
def calc(members):
s = 1;
for n in members:
s = s * n * n;
return s;
print(calc([1,2,3]));
def calc(*members):
s = 1;
for n in members:
s = s * n * n;
return s;
print(calc(1,2));
arr = [1,2,3];
print(calc(*arr));
def person(name,age,**kw):
print(name,age,kw);
person('name',23,sex= 1,city = 'beijing');