1、print('hello world')
2、python并没有long型，int型可以是任意大小的整数
3、string类型，单引号和双引号没区别。三引号表示多行：
'''This is a multi-line string. This is the first line.
This is the second line.
"What's your name?," I asked.
He said "Bond, James Bond."
'''5、关于fromat()函数
一般这么写：
age = 20
name = 'Swaroop'
print('{0} was {1} years old when he wrote this book'.format(name, age))
print('Why is {0} playing with that python?'.format(name))print('{} was {} years old when he wrote this book'.format(name, age))
print('Why is {} playing with that python?'.format(name))name + ' is ' + str(age) + ' years old'# decimal (.) precision of 3 for float '0.33333'
print('{0:.5f}'.format(1.0/3))
# fill with underscores (_) with the text centered
# (^) to 11 width '___hello___'
print('{0:_^11}'.format('hello'))print('a', end='')
print('b', end='')from __future__ import print_function'What\'s your name?'8、关于physical line和logical line. physical line是编辑器的一行， logical line是python编译器所识别的一行。
如果在一行里写多个语句，用；隔开，但是一般在python代码中最好不要出现分号，所以我们不建议这么写代码：
i = 5;
print(i);i = 5; print(i);
i = 5; print(i)最好，一个语句一行：
i = 5
print(i)9、python中，从不用{}来对代码进行分组，只用缩进！python中标准的缩进是4个空格键
10、if语句：
number = 23
guess = int(input('Enter an integer : '))
if guess == number:
# New block starts here
print('Congratulations, you guessed it.')
print('(but you do not win any prizes!)')
# New block ends here
elif guess < number:
# Another block
print('No, it is a little higher than that')
# You can do whatever you want in a block ...
else:
print('No, it is a little lower than that')
# you must have guessed > number to reach here
print('Done')
# This last statement is always executed,
# after the if statement is executed.number = 23
running = True
while running:
guess = int(input('Enter an integer : '))
if guess == number:
print('Congratulations, you guessed it.')
# this causes the while loop to stop
running = False
elif guess < number:
print('No, it is a little higher than that.')
else:
print('No, it is a little lower than that.')
else:
print('The while loop is over.')
# Do anything else you want to do here
print('Done')for i in range(1, 5):
print(i)
else:
print('The for loop is over')break语句：是跳出整个for或者while循环
continue语句：是告诉程序跳出当前循环，直接执行下一循环
while True:
s = input('Enter something : ')
if s == 'quit':
break
if len(s) < 3:
print('Too small')
continue
print('Input is of sufficient length')
# Do other kinds of processing here...x = 50
def func(x):
print('x is', x)
x = 2
print('Changed local x to', x)
func(x)
print('x is still', x) #x的值依然是50x = 50
def func():
global x #是全局变量
print('x is', x)
x = 2
print('Changed global x to', x)
func()
print('Value of x is', x) #x的值变为2def total(a=5, *numbers, **phonebook):
print('a', a)
#iterate through all the items in tuple
for single_item in numbers:
print('single_item', single_item)
#iterate through all the items in dictionary
for first_part, second_part in phonebook.items():
print(first_part,second_part)
print(total(10,1,2,3,Jack=1123,John=2231,Inge=1560))a 10
single_item 1
single_item 2
single_item 3
Inge 1560
John 2231
Jack 1123
Noneimport os
print(os.getcwd())一般不建议from ... import（使用的时候可以省去moduel名，所以可能会造成冲突），使用import ...更妥（不可省）
每个python module都有一个__name__属性，可以通过该属性判断，该moduel是自己在运行还是正在被import
if __name__ == '__main__':
print('This program is being run by itself')
else:
print('I am being imported from another module')可以这么说，每个python程序都可以看成是一个module。e.g.
mymodule.py (该.py文件 为module）
def say_hi():
print('Hi, this is mymodule speaking.')
__version__ = '0.1'import mymodule
mymodule.say_hi()
print('Version', mymodule.__version__)from mymodule import say_hi, __version__
say_hi()
print('Version', __version__)21、python数据结构有：List, Tuple, Dictionary, Set, Sequence, Reference. 具体用法将单独做笔记
22、类class,首先看一个简单的class的例子，了解python中的类怎么使用
class Person:
def __init__(self, name):
self.name = name
def say_hi(self):
print('Hello, my name is', self.name)
p = Person('Swaroop')
p.say_hi()下面详细看重点：class variable, object variable, classmethod. 还是先看例子：
class Robot:
"""Represents a robot, with a name."""
# A class variable, counting the number of robots
population = 0 #类变量，通过Robot.population来访问，并不是通过self.population来访问
def __init__(self, name):
"""Initializes the data."""
self.name = name # name是object 变量，通过self.name访问
print("(Initializing {})".format(self.name))
# When this person is created, the robot
# adds to the population
Robot.population += 1
def die(self):
"""I am dying."""
print("{} is being destroyed!".format(self.name))
Robot.population -= 1
if Robot.population == 0:
print("{} was the last one.".format(self.name))
else:
print("There are still {:d} robots working.".format(
Robot.population))
def say_hi(self):
"""Greeting by the robot.
Yeah, they can do that."""
print("Greetings, my masters call me {}.".format(self.name))
@classmethod
def how_many(cls): #类似于C++ 的静态函数，类的所有实例对象共享
"""Prints the current population."""
print("We have {:d} robots.".format(cls.population))既然提到了类的继承，看下面一个继承的例子：
class SchoolMember:
'''Represents any school member.'''
def __init__(self, name, age):
self.name = name
self.age = age
print('(Initialized SchoolMember: {})'.format(self.name))
def tell(self):
'''Tell my details.'''
print('Name:"{}" Age:"{}"'.format(self.name, self.age), end=" ")
class Teacher(SchoolMember):
'''Represents a teacher.'''
def __init__(self, name, age, salary):
SchoolMember.__init__(self, name, age)
self.salary = salary
print('(Initialized Teacher: {})'.format(self.name))
def tell(self):
SchoolMember.tell(self)
print('Salary: "{:d}"'.format(self.salary))
class Student(SchoolMember):
'''Represents a student.'''
def __init__(self, name, age, marks):
SchoolMember.__init__(self, name, age)
self.marks = marks
print('(Initialized Student: {})'.format(self.name))
def tell(self):
SchoolMember.tell(self)
print('Marks: "{:d}"'.format(self.marks))
t = Teacher('Mrs. Shrividya', 40, 30000)
s = Student('Swaroop', 25, 75)
# prints a blank line
print()
members = [t, s]
for member in members:
# Works for both Teachers and Students
member.tell()这里的tell()函数类似于接口，但又不全是接口，可以在派生类中复写。然后统一访问
23、关于输入输出
输入：
something = input("Enter text: ")关于文件的读写：（读写的mode)）
# Open for 'w'riting
f = open('poem.txt', 'w')
# Write text to file
f.write(poem)
# Close the file
f.close()import pickle
# The name of the file where we will store the object
shoplistfile = 'shoplist.data'
# The list of things to buy
shoplist = ['apple', 'mango', 'carrot']
# Write to the file
f = open(shoplistfile, 'wb')
# Dump the object to a file
pickle.dump(shoplist, f)
f.close()
# Destroy the shoplist variable
del shoplist
# Read back from the storage
f = open(shoplistfile, 'rb')
# Load the object from the file
storedlist = pickle.load(f)
print(storedlist)以utf-8格式读写：
# encoding=utf-8
import io
f = io.open("abc.txt", "wt", encoding="utf-8")
f.write(u"Imagine non-English language here")
f.close()
text = io.open("abc.txt", encoding="utf-8").read()
print(text)24、python关于异常的处理
首先，try...except...else...：
try:
text = input('Enter something --> ')
except EOFError:
print('Why did you do an EOF on me?')
except KeyboardInterrupt:
print('You cancelled the operation.')
else: #执行到这，代表没遇到异常
print('You entered {}'.format(text))import sys
import time
f = None
try:
f = open("poem.txt")
# Our usual file-reading idiom
while True:
line = f.readline()
if len(line) == 0:
break
print(line, end='')
sys.stdout.flush()
print("Press ctrl+c now")
# To make sure it runs for a while
time.sleep(2)
except IOError:
print("Could not find file poem.txt")
except KeyboardInterrupt:
print("!! You cancelled the reading from the file.")
finally: #肯定被执行
if f:
f.close()
print("(Cleaning up: Closed the file)")with open("poem.txt") as f:
for line in f:
print(line, end='')