In text files (those opened without a b in the mode string), only seeks seek ( - 3, 2 ) # Go to the 3rd byte before the end 13 > f. seek ( 5 ) # Go to the 6th byte in the file 5 > f. Using with is also much shorter than writing The advantage is that the file is properly closedĪfter its suite finishes, even if an exception is raised at some It is good practice to use the with keyword when dealing To file data is fine for text files, but will corrupt binary data like that in Text mode, the default is to convert occurrences of \n back to In text mode, the default when reading is to convert platform-specific lineĮndings ( \n on Unix, \r\n on Windows) to just \n. You can not specify encoding when opening file in binary mode. Recommended unless you know that you need to use a different encoding.Īppending a 'b' to the mode opens the file in binary mode.īinary mode data is read and written as bytes objects. If encoding is not specified, the default is platform dependentīecause UTF-8 is the modern de-facto standard, encoding="utf-8" is Strings from and to the file, which are encoded in a specific encoding. Normally, files are opened in text mode, that means, you read and write The mode argument is optional 'r' will be assumed if it’s 'a' opens the file for appending any data written to the file isĪutomatically added to the end. mode can be 'r' when the file will only be read, 'w'įor only writing (an existing file with the same name will be erased), and The second argument isĪnother string containing a few characters describing the way in which the file The first argument is a string containing the filename. > f = open ( 'workfile', 'w', encoding = "utf-8" ) It understands about plus and minus signs: There is another method, str.zfill(), which pads a numeric string on the (If you really want truncation you can always add a Long, they don’t truncate it, but return it unchanged this will mess up yourĬolumn lay-out but that’s usually better than the alternative, which would be Not write anything, they just return a new string. Similar methods str.ljust() and str.center(). The str.rjust() method of string objects right-justifies a string in aįield of a given width by padding it with spaces on the left. Way print() works: it always adds spaces between its arguments.) (Note that the one space between each column was added by the This allows greaterĬontrol over how the value is formatted. Prefixing the string with f or F and writing expressions asĪn optional format specifier can follow the expression. Short) let you include the value of Python expressions inside a string by Formatted String Literals ¶įormatted string literals (also called f-strings for $x and replacing them with values from a dictionary, but offers much lessĬontrol of the formatting. Yet another way to substitute values into strings, using placeholders like The string module contains a Template class that offers hello = 'hello, world \n ' > hellos = repr ( hello ) > print ( hellos ) 'hello, world\n' > # The argument to repr() may be any Python object. > # The repr() of a string adds string quotes and backslashes. Particular, have two distinct representations. Many values, such as numbers or structures like lists andĭictionaries, have the same representation using either function. Representation for human consumption, str() will return the same value as For objects which don’t have a particular Which can be read by the interpreter (or will force a Synta圎rror if The str() function is meant to return representations of values which areįairly human-readable, while repr() is meant to generate representations Variables for debugging purposes, you can convert any value to a string with When you don’t need fancy output but just want a quick display of some String type has some methods that perform useful operations for padding format ( yes_votes, percentage ) ' 42572654 YES votes 49.67%'įinally, you can do all the string handling yourself by using string slicing andĬoncatenation operations to create any layout you can imagine.
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