file handling using pickle

try.py:

import pickle

f=open('abc.dat','w')
x=[320,315,316]
y=pickle.load(f)
f.close()
f=open('abc.dat','w')
for i in x:
        y.append(i)
pickle.dump(y,f)
f.close()

use.py

import pickle
import os

os.system('try.py')
f=open('abc.dat', 'r')
print "abc.dat = "
x=pickle.load(f)
print x
print "end of abc.dat"
f.close();
y=x[:]
for z in x:
        y.remove(z)
        print "removing " + str(z)
        print str(y) + " and " + str(x)
        f=open('abc.dat', 'w')
        pickle.dump(y, f)
        f.close()

error:

Traceback (most recent call last):
  File "G:\parin\new start\use.py", line 7, in <module>开发者_运维知识库
    x=pickle.load(f)
  File "C:\Python26\lib\pickle.py", line 1370, in load
    return Unpickler(file).load()
  File "C:\Python26\lib\pickle.py", line 858, in load
        dispatch[key](self)
  File "C:\Python26\lib\pickle.py", line 880, in load_eof
    raise EOFError
EOFError

The error is in try.py:

f=open('abc.dat','w')
y=pickle.load(f)

Note that the 'w' mode resets the file to size 0 (i.e. deletes its content). Pass 'r' or nothing at all to open abc.dat for reading.

Example doesn't work for me. try.py fails when the file doesn't exist.

My big recommendation, though, is to look at using JSON instead of pickle, as you'll have more cross-platform flexibility and the interface is more flexible.

For example, use this to create a file of JSON lines:

import json,random

with open("data.txt","w") as f:
    for i in range(0,10):
        info = {"line":i,
                "random":random.random()}
        f.write(json.dumps(info)+"\n")

(Make info whatever you want, obviously.)

Then use this to read them:

import json

for line in open("data.txt"):
    data = json.loads(line)
    print("data:" + str(data))