python练习题集合-2

[root@localhost py]# echo 1234567890 > cc.txt

[root@localhost py]# cat file3.py 
#!/usr/bin/env python
from sys import argv
from os.path import exists
script,from_file,to_file = argv
print "Copying from %s to %s" %(from_file,to_file)

# we could do these two on one line too,how?
input = open(from_file)
indata = input.read()

print "The input file is %d bytes long"%len(indata)
print "Does the output file exist? %r"%exists(to_file)

print "Ready,hit RETURN to continue, CTRL-C to abort."
raw_input()

output = open(to_file,‘w‘)
output.write(indata)
print "Alright,all done."
output.close()
input.close()

[root@localhost py]# python file3.py cc.txt dd.txt
Copying from cc.txt to dd.txt
The input file is 11 bytes long
Does the output file exist? True
Ready,hit RETURN to continue, CTRL-C to abort.

Alright,all done.

[root@localhost py]# cat func1.py 
#!/usr/bin/env python

# this is like you scripts with argv
def print_two(*args):
arg1,arg2 = args
print "arg1:%r,arg2:%r" %(arg1,arg2)

# ok,that *args is actually pointless,we can just do this 
def print_two_again(arg1,arg2):
print "arg1:%r,arg2:%r" %(arg1,arg2)

# this just takes one argument
def print_one(arg1):
print "arg1:%r"% arg1

# this one takes no arguments
def print_none():
print "I got nothing."

print_two(‘zen‘,‘hello‘)
print_two_again(‘ZEN‘,‘HELLO‘)
print_one(‘First!‘)
print_none()

[root@localhost py]# python func1.py

arg1:‘zen‘,arg2:‘hello‘
arg1:‘ZEN‘,arg2:‘HELLO‘
arg1:‘First!‘
I got nothing.

[root@localhost py]# cat func2.py 
#!/usr/bin/env python
def cheese_and_crackers(cheese_count, boxes_of_crackers):
print "You have %d cheeses!" % cheese_count
print "You have %d boxes of crackers!" % boxes_of_crackers
print "Man that‘s enough for a party!"
print "Get a blanket.\n"
print "We can just give the function numbers directly:"

cheese_and_crackers(20, 30)

print "OR, we can use variables from our script:"
amount_of_cheese = 10
amount_of_crackers = 50
cheese_and_crackers(amount_of_cheese, amount_of_crackers)

print "We can even do math inside too:"
cheese_and_crackers(10 + 20, 5 + 6)
print "And we can combine the two, variables and math:"
cheese_and_crackers(amount_of_cheese + 100, amount_of_crackers + 1000)

[root@localhost py]# python func2.py
We can just give the function numbers directly:
You have 20 cheeses!
You have 30 boxes of crackers!
Man that‘s enough for a party!
Get a blanket.

OR, we can use variables from our script:
You have 10 cheeses!
You have 50 boxes of crackers!
Man that‘s enough for a party!
Get a blanket.

We can even do math inside too:
You have 30 cheeses!
You have 11 boxes of crackers!
Man that‘s enough for a party!
Get a blanket.

And we can combine the two, variables and math:
You have 110 cheeses!
You have 1050 boxes of crackers!
Man that‘s enough for a party!
Get a blanket.

[root@localhost py]# cat aa.txt 
aaaaaa
bbbbbb
cccccc

[root@localhost py]# cat func-file.py 

#!/usr/bin/env python
from sys import argv
script, input_file = argv
def print_all(f):
print f.read()
def rewind(f):
f.seek(0)
def print_a_line(line_count, f):
print line_count, f.readline()
current_file = open(input_file)

print "First let‘s print the whole file:\n"
print_all(current_file)

print "Now let‘s rewind, kind of like a tape."
rewind(current_file)
print "Let‘s print three lines:"

current_line = 1
print_a_line(current_line, current_file)

current_line = current_line + 1
print_a_line(current_line, current_file)

current_line = current_line + 1
print_a_line(current_line, current_file)

[root@localhost py]# python func-file.py aa.txt 
First let‘s print the whole file:

aaaaaa
bbbbbb
cccccc

Now let‘s rewind, kind of like a tape.
Let‘s print three lines:
1 aaaaaa

2 bbbbbb

3 cccccc

[root@localhost py]# cat func-return.py 
#!/usr/bin/env python
# -*- coding:utf-8 -*-
def add(a, b):
print "ADDING %d + %d" % (a, b)
return a + b
def subtract(a, b):
print "SUBTRACTING %d - %d" % (a, b)
return a - b
def multiply(a, b):
print "MULTIPLYING %d * %d" % (a, b)
return a * b
def divide(a, b):
print "DIVIDING %d / %d" % (a, b)
return a / b

print "Let‘s do some math with just functions!"
age = add(30, 5)
height = subtract(78, 4)
weight = multiply(90, 2)
iq = divide(100, 2)
print "Age: %d, Height: %d, Weight: %d, IQ: %d" % (age, height,weight, iq)

# A puzzle for the extra credit, type it in anyway.# pullzle:智力题
print "Here is a puzzle."
what = add(age, subtract(height, multiply(weight, divide(iq,2))))
print "That becomes: ", what, "Can you do it by hand?"

[root@localhost py]# python func-return.py
Let‘s do some math with just functions!
ADDING 30 + 5
SUBTRACTING 78 - 4
MULTIPLYING 90 * 2
DIVIDING 100 / 2
Age: 35, Height: 74, Weight: 180, IQ: 50
Here is a puzzle.
DIVIDING 50 / 2
MULTIPLYING 180 * 25
SUBTRACTING 74 - 4500
ADDING 35 + -4426
That becomes: -4391 Can you do it by hand?

[root@localhost py]# cat practise.py 
#!/usr/bin/env python
print "Let‘s practice everything."
print ‘You\‘d need to know \‘bout escapes with \\ that do \nnewlines and \t tabs.‘
poem = """
\tThe lovely world
with logic so firmly planted
cannot discern \n the needs of love
nor comprehend passion from intuition
and requires an explanation
\n\t\twhere there is none.
"""
print "--------------"
print poem
print "--------------"
five = 10 - 2 + 3 - 6
print "This should be five: %s" % five

def secret_formula(started):
jelly_beans = started * 500
jars = jelly_beans / 1000
crates = jars / 100
return jelly_beans, jars, crates
start_point = 10000
beans, jars, crates = secret_formula(start_point)
print "With a starting point of: %d" % start_point
print "We‘d have %d beans, %d jars, and %d crates." % (beans,jars, crates)
start_point = start_point / 10
print "We can also do that this way:"
print "We‘d have %d beans, %d jars, and %d crates." % secret_formula(start_point)

[root@localhost py]# python practise.py 
Let‘s practice everything.
You‘d need to know ‘bout escapes with \ that do 
newlines and tabs.
--------------

The lovely world
with logic so firmly planted
cannot discern 
the needs of love
nor comprehend passion from intuition
and requires an explanation

where there is none.

--------------
This should be five: 5
With a starting point of: 10000
We‘d have 5000000 beans, 5000 jars, and 50 crates.
We can also do that this way:
We‘d have 500000 beans, 500 jars, and 5 crates.

[root@localhost py]# cat practise2.py 
#!/usr/bin/env python
def break_words(stuff):
"""This function will break up words for us."""
words = stuff.split(‘‘)
return words
def sort_words(words):
"""Sorts the words."""
return sorted(words)
def print_first_word(words):
"""Prints the first word after popping it off."""
word = words.pop(0)
print word
def print_last_word(words):
"""Prints the last word after popping it off."""
word = words.pop(-1)
print word
def sort_sentence(sentence):
"""Takes in a full sentence and returns the sorted words."""
words = break_words(sentence)
return sort_words(words)
def print_first_and_last(sentence):
"""Prints the first and last words of the sentence."""
words = break_words(sentence)
print_first_word(words)
print_last_word(words)
def print_first_and_last_sorted(sentence):
"""Sorts the words then prints the first and last one."""
words = sort_sentence(sentence)
print_first_word(words)
print_last_word(words)