How to open a file to read and write
Opening Files
You can open files with the open function, which has the following syntax:
open(name[, mode[, buffering]])
The open function takes a file name as its only mandatory argument, and returns a file object. The mode and buffering arguments are optional.
The following code opens a file called somefile.txt stored in the directory C:\text,
f = open(r'C:\text\somefile.txt')
If the file doesn't exist, you may see an exception traceback. If you use open with only a file name, the file is opened in read from.
If you want to write to the file, you have to state that explicitly, supplying a mode. The mode argument are summarized in the following table.
| Value | Description |
|---|---|
| 'r' | Read mode |
| 'w' | Write mode |
| 'a' | Append mode |
| 'b' | Binary mode (added to other mode) |
| '+' | Read/write mode (added to other mode) |
The write mode enables you to write to the file.
The '+' can be added to any of the other modes to indicate that both reading and writing is allowed. So 'r+' can be used when opening a text file for reading and writing.
The 'b' mode changes the way the file is handled. rb' to read a binary file.
turn file content to list or tuple
print list(open('script1.py'))
print tuple(open('script1.py'))
print '&&'.join(open('script1.py'))
# www .j a va 2 s . c o m
a, b, c, d = open('script1.py')
print a
print b
print c
print d
Working with File Objects
open returns a file object, which has methods and attributes for getting
information about and manipulating the opened file.
f = open("aFile.txt", "rb")
# from ww w .j av a 2 s . c o m
print f
print f.mode
print f.name
Use file pointer to get file content
f = open('somefile.txt', 'w')
print >> f, 'This is the first line'
print >> f, 'This is the second line'
print >> f, 'This is the third line'
f.close()# from w ww. ja va2 s . c o m