Python 基础 二

使用 python 2.6 源于：http://wiki.jikexueyuan.com/project/learn-python-hard-way/

接收参数： from sys import argv

script, first, second, third = argv

print “The script is called:”, script print “Your first variable is:”, first print “Your second variable is:”, second print “Your third variable is:”, third

$ python ex13.py first 2nd 3rd The script is called: ex13.py Your first variable is: first Your second variable is: 2nd Your third variable is: 3rd

exercise14 提示和传递： from sys import argv

script, user_name = argv prompt = ‘> ‘

print “Hi %s, I’m the %s script.” % (user_name, script) print “I’d like to ask you a few questions.” print “Do you like me %s?” % user_name likes = raw_input(prompt)

print “Where do you live %s?” % user_name lives = raw_input(prompt)

print “What kind of computer do you have?” computer = raw_input(prompt)

print “”” Alright, so you said %r about liking me. You live in %r. Not sure where that is. And you have a %r computer. Nice. “”” % (likes, lives, computer)

exercise16.读写文件 •close – 关闭文件。跟你编辑器的 文件->保存.. 一个意思。 •read – 读取文件内容。你可以把结果赋给一个变量。 •readline – 读取文本文件中的一行。 •truncate – 清空文件，请谨慎使用该命令。 •write(‘stuff’) – 将 stuff 写入文件。

from sys import argv

script, filename = argv print “Opening the file…” target = open(filename, ‘w’) print target .read() print “Truncating the file. Goodbye!” target.truncate()

print “Now I’m going to ask you for three lines.”

line1 = raw_input(“line 1: “) line2 = raw_input(“line 2: “) line3 = raw_input(“line 3: “)

print “I’m going to write these to the file.”

target.write(line1) target.write(“\n”) target.write(line2) target.write(“\n”) target.write(line3) target.write(“\n”)

print “And finally, we close it.” target.close()

‘w’表示”以写（write）模式。有’r’表示只读模式，’a’表示追加模式 w+ 打开可读写文件，若文件存在则文件长度清为零，即该文件内容会消失。若文件不存在则建立该文件。 r+ 以可读写方式打开文件，该文件必须存在。 a+ 以附加方式打开可读写的文件。若文件不存在，则会建立该文件，如果文件存在，写入的数据会被加到文件尾后，即文件原先的内容会被保留

exercise17.更多文件操作

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, how? in_file = open(from_file) indata = in_file.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()

out_file = open(to_file, ‘w’) out_file.write(indata)

print “Alright, all done.”

out_file.close() in_file.close()

exercise18.命名, 变量, 代码, 函数 函数定义：

def print_one(arg1): print “arg1: %r” % arg1

print_one(“First!”)

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)

定义 ex25.py 如下： def break_words(stuff): “”“This function will break up words for us.”“” words = stuff.split(’ ‘) return words

$ python import ex25 sentence = “All good things come to those who wait.” words = ex25.break_words(sentence) words