参考文献：廖雪峰老师的官网
1.数据类型转换
>>> int('123')
123
>>> int(12.34)
12
>>> float('12.34')
12.34
>>> str(1.23)
'1.23
'>>> str(100)
'100'
>>> bool(1)
True
>>> bool('')
False
int(),bool(),str();
2.定义函数
# -*- coding: utf-8 -*-
def my_abs(x):
if x >= 0:
return x
else:
return -x
print(my_abs(-99))
3.空函数
def nop():
pass
pass语句什么都不做，那有什么用？实际上pass可以用来作为占位符，比如现在还没想好怎么写函数的代码，就可以先放一个pass，让代码能运行起来。
4.可变参数
>>> def calc(number):
... sum = 0
... for n in number:
... sum = sum + n * n
... return sum
>>> calc([1,2,3,4])
30
5.关键参数
def person(name, age, **kw):
print('name:', name,'age:', age,'other:', kw)
>>> person('Bob',35, city='Beijing')
name: Bob age:35other: {'city':'Beijing'}
>>> person('Adam',45, gender='M', job='Engineer')
name: Adam age:45other: {'gender':'M','job':'Engineer'}
>>> extra = {'city':'Beijing','job':'Engineer'}
>>> person('Jack',24, **extra)
name: Jack age:24other: {'city':'Beijing','job':'Engineer'}
