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Python Language Reference Manual
by Guido van Rossum and Fred L. Drake, Jr.
Paperback (6"x9"), 120 pages
ISBN 0954161785
RRP £12.95 ($19.95)

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6.6 The print statement

print_stmt "print"
([expression ("," expression)* [","]] | ">>" expression [("," expression)+] [","])

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.

ISBN 0954161785Python Language Reference ManualSee the print edition