循环的写法

>>> names = ['michael','bob','tracy']
>>> for name in names:
...     print(name)
...
michael
bob
tracy
>>> sum =0
>>> for x in [1,2,3,4,5,6,7,8,9,10];
  File "<stdin>", line 1
    for x in [1,2,3,4,5,6,7,8,9,10];
                                   ^
SyntaxError: invalid syntax
>>> for x in [1,2,3,4,5,6,7,8,9,10]:
...     sum = sum + x
... print(sum)
  File "<stdin>", line 3
    print(sum)
    ^
SyntaxError: invalid syntax
>>> print(sum)
0
>>> for x in [1,2,3,4,5,6,7,8,9,10]:
...     sum = sum + x
...
>>> print(sum)
55
>>> list(range(5))
[0, 1, 2, 3, 4]
>>> sum = 0
>>> for x in range(101):
...     sum = sum +x
...
>>> print(sum)
5050
>>> sum = 0
>>> n =99
>>> while n>0:
...     sum+=n
...     n-=2
...
>>> print(sum)
2500
>>> n=1
>>> while n<=100
  File "<stdin>", line 1
    while n<=100
               ^
SyntaxError: invalid syntax
>>> while n<=100:
...     if n>10:
...         break
...     print(n)
...     n+=1
...
1
2
3
4
5
6
7
8
9
10
>>> n=0
>>> while n<10:
...     n+=1
...     if n%2==0:
...         continue
...     print(n)
...
1
3
5
7
9

dict和set

>>> names = ['micheal','bob','tracy']
>>> score = [95,75,85]
>>>
>>> d={'micheal':95,'bob':75,'tracy':85}
>>> d['micheal'}
  File "<stdin>", line 1
    d['micheal'}
               ^
SyntaxError: closing parenthesis '}' does not match opening parenthesis '['
>>> d{'micheal'}
  File "<stdin>", line 1
    d{'micheal'}
     ^
SyntaxError: invalid syntax
>>> d['micheal']
95
>>> d['adam']=67
>>> d['adam']
67
>>> 'tom' in d
False
>>> d.get('tom')
>>> d.get('tom',-0)
0
>>> d.pop('micheal')
95
>>> d
{'bob': 75, 'tracy': 85, 'adam': 67}
>>> s=set([1,2,3])
>>> s
{1, 2, 3}
>>> s = set([1,1,2,3,2,3])
>>> s
{1, 2, 3}
>>> s.add(5)
>>> s
{1, 2, 3, 5}
>>> s,add(1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'add' is not defined
>>> s.add(1)
>>> s
{1, 2, 3, 5}
>>> s.remove(2)
>>> s
{1, 3, 5}

可变对象和不可变对象

>>> a = ['a','b','d','c']
>>> a.sort
<built-in method sort of list object at 0x000002AABFFCF500>
>>> a.sort()
>>> a
['a', 'b', 'c', 'd']
>>> a='abc'
>>> a,replace('a','A')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'replace' is not defined
>>> a.replace('a','A')
'Abc'
>>> a
'abc'

调用函数

>>> help(abs)
Help on built-in function abs in module builtins:

abs(x, /)
    Return the absolute value of the argument.

>>> abs(-90)
90
>>> abs (1,2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: abs() takes exactly one argument (2 given)
>>> max(1,2,3,4,90.111)
90.111
>>> abs('abc')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: bad operand type for abs(): 'str'
>>> int(11.34)
11
>>> int('123')
123
>>> bool(1)
True
>>> bool()
False
>>> a= abs
>>> a(-1)
1
>>>

定义函数

>>> def my_abs()x:
  File "<stdin>", line 1
    def my_abs()x:
                ^
SyntaxError: invalid syntax
>>> def my_abs(x):
...     if x >=0:
...         return x
...     else:
...         return -x
...
>>> print(my_abs(-99))
99
>>> def nop():
...     pass
...
>>> nop()
>>> my_abs(-1,-2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: my_abs() takes 1 positional argument but 2 were given
>>> abs(-1,-2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: abs() takes exactly one argument (2 given)
>>> my_abs('a')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in my_abs
TypeError: '>=' not supported between instances of 'str' and 'int'
>>> abs('a')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: bad operand type for abs(): 'str'
>>> def my_abs(x):
...     if not isinstance(x,(int,float)):
...         raise TypeError('bad operand type')
...     if x>=0:
...         return x
...     else:
...         return -x
...
>>> my_abs('a')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in my_abs
TypeError: bad operand type
>>> import math
>>> def move(x,y,step,angle=0):
...     nx = x+step*math.cos(angle)
...     ny = y-step*math.sin(angle)
...     return nx ny
  File "<stdin>", line 4
    return nx ny
              ^
SyntaxError: invalid syntax
>>> def move(x,y,step,angle=0):
...     nx = x+step*math.cos(angle)
...     ny = y-step*math.sin(angle)
...     return nx,ny
...
>>> x,y=move(100,100,60,math.pi/6)
>>> print(x,y)
151.96152422706632 70.0
>>> r=move(100,100,60,math.pi/6)
>>> print(r)
(151.96152422706632, 70.0)