调用函数

函数：

http://docs.python.org/2/library/functions.html#abs

# -*- coding: UTF-8 -*-
help(abs)

C:Python27python.exe C:/Users/TLCB/PycharmProjects/untitled/t1.py
Help on built-in function abs in module __builtin__:

abs(...)
    abs(number) -> number
    
    Return the absolute value of the argument.

# -*- coding: UTF-8 -*-
print abs(-20)

C:Python27python.exe C:/Users/TLCB/PycharmProjects/untitled/t1.py
20

# -*- coding: UTF-8 -*-
print abs(-20,1)

C:Python27python.exe C:/Users/TLCB/PycharmProjects/untitled/t1.py
Traceback (most recent call last):
  File "C:/Users/TLCB/PycharmProjects/untitled/t1.py", line 2, in <module>
    print abs(-20,1)
TypeError: abs() takes exactly one argument (2 given)

Process finished with exit code 1

# -*- coding: UTF-8 -*-
print abs('-20')

C:Python27python.exe C:/Users/TLCB/PycharmProjects/untitled/t1.py
Traceback (most recent call last):
  File "C:/Users/TLCB/PycharmProjects/untitled/t1.py", line 2, in <module>
    print abs('-20')
TypeError: bad operand type for abs(): 'str'

数据类型转换:

>>> '123'
'123'
>>> int('123')
123
>>>