Python3中简单的文件操作及两个简单小实例分享

input = open(filepath,mode)

input = open("/Users/sherlockblaze/Documents/pythonworkspace/Test.txt","r")

input = open("Test.txt","r")

input = open(r"d:\pythonworkspace\Test.txt","r")

input = open("d:\\pythonworkspace\\Test.txt","r")

def main():
 input = open("Test.txt","w")
 input.write("SherlockBlaze")
 input.write("\t is the most handsome guy!\n")
 input.close()
 
main()

import os.path
is os.paht.isfile("Test.txt"):
 print("Test.txt exists")
else:
 print("Test.txt doesn't exists")

def main():
 filename = input("Enter a filename: ").strip()
 infile = open(filename,"r")
 counts = 26 * [0]
 for line in infile:
 countLetters(line.lower(),counts)
 for i in range(len(counts)):
 if counts[i] != 0:
 print(chr(ord('a') + i) + "appears " + str(counts[i])
 + (" time" if counts[i] == 1 else " times"))
 infile.close()
def countLetters(line,counts):
 for ch in line:
 if ch.isalpha():
 counts[ord(ch) - ord('a')] += 1
main()

import sys
import urllib
import urllib.request
import os.path
def download(url,num_retries = 2):
 print ('Downloading:',url)
 try:
 html = urllib.request.urlopen(url).read()
 except urllib.URLError as e:
 print ('Download error:',e.reason)
 html = None
 if num_retries > 0:
 if hasattr(e,'code') and 500 <= e.code <600:
 return download(url,num_retries-1)
 return html
def main():
 url = input("Enter a url:\n").strip()
 f2 = input("Enter a target file:\n").strip()
 if os.path.isfile(f2):
 print(f2 + " already exists")
 sys.exit()
 html = download(url)
 target = open(f2,"w")
 content = html.decode(encoding="utf-8")
 target.write(content)
 target.close()
main()