Skip to main content
Engineering LibreTexts

10.11: Reading from Files

  • Page ID
    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    To read the content of a file, pass the string 'r' instead of 'w' to the open() function. Then call the readlines() method on the file object to read in the contents of the file. Last, close the file by calling the close() method.

    >>> textFile = open('hello.txt', 'r')
    >>> content = textFile.readlines()
    >>> textFile.close()

    The readlines() method returns a list of strings: one string for each line of text in the file:

    >>> content
    ['This will be the content of the file.\n', 'Hello world!\n']

    If you want to re-read the contents of that file, you will have to call close() on the file object and re-open it.

    As an alternative to readlines(), you can also call the read() method, which will return the entire contents of the file as a single string value:

    >>> textFile = open('hello.txt', 'r')
    >>> content =
    >>> content
    'This will be the content of the file.\nHello world!\n'

    On a side note, if you leave out the second parameter to the open() function, Python will assume you mean to open the file in read mode. So open('foobar.txt', 'r') and open('foobar.txt') do the exact same thing.

    This page titled 10.11: Reading from Files is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by Al Sweigart via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.