Troubles with file operations

[YarrOfDoom]

I've started out on python a couple of weeks ago, and today I came to "7. Input and Output" in the python docs tutorial. So I tried some of it myself, but it always ends with completely mashed up output and error messages and my computer beeping like hell. So what is wrong with this code to cause all that?

f = open('C:/users/username/Documents/python/workfiles/testfile', 'r+')
f.write('teststring')
s = f.read()
print s
f.close()
f = open('C:/users/username/Documents/python/workfiles/testfile', 'w')
testobject = ['string', 12, 12.3, ('tuple','scond')]
pickle.dump(testobject, f)
f.close()
f = open('C:/users/username/Documents/python/workfiles/testfile', 'r')
o = pickle.load(f)
print o
f.close()

[boxfish]

Looks like pickle's load function returns some kind of special pickle object with a weird way of printing. Try casting it to a list:

f = open('C:/test.txt', 'r')
o = list(pickle.load(f))
print o
f.close()
 

Hope this helps.

[bvdet]

I've started out on python a couple of weeks ago, and today I came to "7. Input and Output" in the python docs tutorial. So I tried some of it myself, but it always ends with completely mashed up output and error messages and my computer beeping like hell. So what is wrong with this code to cause all that?

f = open('C:/users/username/Documents/python/workfiles/testfile', 'r+')
f.write('teststring')
s = f.read()
print s
f.close()
f = open('C:/users/username/Documents/python/workfiles/testfile', 'w')
testobject = ['string', 12, 12.3, ('tuple','scond')]
pickle.dump(testobject, f)
f.close()
f = open('C:/users/username/Documents/python/workfiles/testfile', 'r')
o = pickle.load(f)
print o
f.close()

The problem is not with pickle. The problem is that strange things can happen when reading and writing to a file and you don't flush the output buffer after a write. Try this:

f = open('test.txt', 'r+')
print f.tell()
f.seek(0, 2)
print f.tell()
f.write('teststring')
print f.tell()
f.flush()
f.seek(0)
print f.tell()
 
s = f.read()
print s
f.close()

The write is appended to the file. Using f.seek(0,2) places the current position at the end of the file. Now try this:

f = open('test.txt', 'r+')
print f.tell()
print f.tell()
f.write('ZZZZZZZZZZ')
print f.tell()
f.flush()
f.seek(0)
print f.tell()
 
s = f.read()
print s
f.close()

The write occurs at the beginning of the file, and overwrites the characters at that position.

[YarrOfDoom]

Thanks, not using flush() was indeed the problem, nothing was mentioned about it in the tutorial, guess they didn't expect people to try everything they explained there in one script.