6.6 The print statement
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print evaluates each expression in turn and writes the
resulting object to standard output (see below). If an object is not a string, it is first
converted to a string using the rules for string conversions. The (resulting or original)
string is then written. A space is written before each object is (converted and) written,
unless the output system believes it is positioned at the beginning of a line. This is the
case (1) when no characters have yet been written to standard output, (2) when the last
character written to standard output is "\n", or (3)
when the last write operation on standard output was not a print
statement. (In some cases it may be functional to write an empty string to standard output
for this reason.) Note: Objects which act like
file objects but which are not the built-in file objects often do not properly emulate
this aspect of the file object's behavior, so it is best not to rely on this.
A "\n" character is written at the end, unless the
print statement ends with a comma. This is the only action if the
statement contains just the keyword print.
Standard output is defined as the file object named stdout in the built-in
module sys. If no such object exists, or if it does not have a write() method, a RuntimeError exception is
raised.
print also has an extended
form, defined by the second portion of the syntax described above. This form is
sometimes referred to as ``print chevron.'' In this form, the
first expression after the >> must evaluate to a ``file-like'' object,
specifically an object that has a write() method as described
above. With this extended form, the subsequent expressions are printed to this file
object. If the first expression evaluates to None, then sys.stdout
is used as the file for output.
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