cedric's bazaar

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====== Reading a file ======

===== Line by line =====
<code python>
>>> for line in open("./dico.txt", "r"):
...   print(line)
... 
ABACA~

ABACULE~

ABAISSABLE~

ABAISSAIENT~

ABAISSAIS~
.
.
.
</code>

===== Classic method =====

<code python>
>>> a_file = None
>>> try:              
...   a_file = open("./dico.txt", "r")
...   text = a_file.read()
... except:
...   print("Error")
... finally:
...   if a_file != None:
...     a_file.close()
... 
>>> 
>>> a_file
<_io.TextIOWrapper name='./dico.txt' encoding='UTF-8'>
>>> a_file.name
'./dico.txt'
</code>

===== The with statement =====
The better solution. No need to use **try: ... except: ...**.\\
Forget the previous method.

<code python>
>>> with open("./dico.txt", "r") as f:
...   text = f.read()
>>>
>>> len(text)
2664170
>>> print(text)
.
.
.
ZYGOMORPHE~
ZYGOMYCETES~
ZYGOMYCETE~
ZYGOPETALE~
ZYGOTE~
ZYMASE~
ZYMOTECHNIE~
ZYMOTIQUE~
ZYTHON~
ZYTHUM~
Z~
</code>

This code calls open(), but it never calls a_file.close(). The with statement starts a code block, like an if statement or a for loop. Inside this code block, you can use the variable a_file as the stream object returned from the call to open(). All the regular stream object methods are available — seek(), read(), whatever you need. When the with block ends, Python calls a_file.close() automatically.