Python (1)

1.

##########if begin

number = 23
guess = int(input('Enter an integer : '))

if guess == number:
    print ('Congratulations, you guessed it.') # New block starts here
    print ("but you do not win any prizes!" )# New block ends here
elif guess < number:
    print ('No, it is a little higher than that') # Another block
    # You can do whatever you want in a block ...
else:
    print ('No, it is a little lower than that')
    # you must have guess > number to reach here

print ('Done')

 

summary: if  ....: ...

　　　　　elif ...: ...

　　　　　else:

#######if end

2.

### help begin

help ("input")

### help end

3.

### while begin

number = 23
running = True

while running:
    guess = int(raw_input('Enter an integer : '))

    if guess == number:
        print 'Congratulations, you guessed it.'
        running = False # this causes the while loop to stop
    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'

 

### while end

4.

### for begin

for i in range(1, 5):
    print i
else:
    print 'The for loop is over'

# range(1,5,2)给出[1,3]

### for end

5.

### break begin

while True:
    s = input('Enter something : ')
    if s == 'quit':
        break
    print 'Length of the string is', len(s)
print 'Done'

### break end

6.

### continue begin

while True:
    s = raw_input('Enter something : ')
    if s == 'quit':
        break
    if len(s) < 3:
        continue
    print 'Input is of sufficient length'
    # Do other kinds of processing here...

### continue end

7.

### def function begin

def sayHello():
    print 'Hello World!' # block belonging to the function

sayHello() # call the function

### def function end

 

8.

### def funciton with parameters begin

def printMax(a, b):
    if a > b:
        print a, 'is maximum'
    else:
        print b, 'is maximum'

printMax(3, 4) # directly give literal values

x = 5
y = 7

printMax(x, y) # give variables as arguments

### def funciton with parameters end

 

9.

### golbal begin

def func():
    global x

    print 'x is', x
    x = 2
    print 'Changed local x to', x

x = 50
func()
print 'Value of x is', x

# global x, y, z

### global end

10.

### def print *x begin

def say(message, times = 1):
    print message * times

say('Hello')
say('World', 5)

### def print *x end

11.

### return begin

#return语句用来从一个函数 返回 即跳出函数

def maximum(x, y):
    if x > y:
        return x
    else:
        return y

print maximum(2, 3)

### return end

12.

### pass begin

def someFunction():
    pass

#pass语句在Python中表示一个空的语句块

###pass end

13.

### DocStrings begin

def printMax(x, y):
    '''Prints the maximum of two numbers.

    The two values must be integers.'''
    x = int(x) # convert to integers, if possible
    y = int(y)

    if x > y:
        print x, 'is maximum'
    else:
        print y, 'is maximum'

printMax(3, 5)
print printMax.__doc__

#文档字符串的惯例是一个多行字符串，它的首行以大写字母开始，句号结尾。第二行是空行，从第三行开始是详细的描述。 强烈建议 你在你的函

#数中使用文档字符串时遵循这个惯例。

### DocStrings end

14.

模块的文件名必须以.py为扩展名

 from sys import argv

 如果你想要输入所有sys模块使用的名字，那么你可以使用from sys import *语句

 15.

### Create module

#!/usr/bin/python
# Filename: mymodule.py

def sayhi():
    print 'Hi, this is mymodule speaking.'

version = '0.1'

# End of mymodule.py

 

#!/usr/bin/python
# Filename: mymodule_demo.py

import mymodule

mymodule.sayhi()
print 'Version', mymodule.version

 ### create module end

### another call module begin

#!/usr/bin/python
# Filename: mymodule_demo.py

from mymodule import sayhi, version
# Alternative:
# from mymodule import *

sayhi()
print 'Version', version

### another call module end

16.

dir函数来列出模块定义的标识符。标识符有函数、类和变量。

当你为dir()提供一个模块名的时候，它返回模块定义的名称列表。如果不提供参数，它返回当前模块中定义的名称列表。

import sys
dir(sys)

dir()