This module implements a file-like class,
StringIO, that reads and
writes a string buffer (also known as memory files). See the description of
file objects for operations (section File Objects). (For
standard strings, see
StringIOobject is created, it can be initialized to an existing string by passing the string to the constructor. If no string is given, the
StringIOwill start empty. In both cases, the initial file position starts at zero.
StringIOobject can accept either Unicode or 8-bit strings, but mixing the two may take some care. If both are used, 8-bit strings that cannot be interpreted as 7-bit ASCII (that use the 8th bit) will cause a
UnicodeErrorto be raised when
The following methods of
StringIO objects require special mention:
Retrieve the entire contents of the “file” at any time before the
close()method is called. See the note above for information about mixing Unicode and 8-bit strings; such mixing can cause this method to raise
import StringIO output = StringIO.StringIO() output.write('First line.\n') print >>output, 'Second line.' # Retrieve file contents -- this will be # 'First line.\nSecond line.\n' contents = output.getvalue() # Close object and discard memory buffer -- # .getvalue() will now raise an exception. output.close()
cStringIO provides an interface similar to that of the
StringIO module. Heavy use of
StringIO.StringIO objects can be
made more efficient by using the function
StringIO() from this module
Return a StringIO-like stream for reading or writing.
Since this is a factory function which returns objects of built-in types, there’s no way to build your own version using subclassing. It’s not possible to set attributes on it. Use the original
StringIOmodule in those cases.
StringIOmodule, this module is not able to accept Unicode strings that cannot be encoded as plain ASCII strings.
Another difference from the
StringIOmodule is that calling
StringIO()with a string parameter creates a read-only object. Unlike an object created without a string parameter, it does not have write methods. These objects are not generally visible. They turn up in tracebacks as
The following data objects are provided as well:
The type object of the objects created by calling
StringIO()with a string parameter.
The type object of the objects returned by calling
StringIO()with no parameters.
There is a C API to the module as well; refer to the module source for more information.
import cStringIO output = cStringIO.StringIO() output.write('First line.\n') print >>output, 'Second line.' # Retrieve file contents -- this will be # 'First line.\nSecond line.\n' contents = output.getvalue() # Close object and discard memory buffer -- # .getvalue() will now raise an exception. output.close()