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In this video, we demonstrate two of the four ways to read a file. Each of these approaches allows you to work with the files in a different way.
Download: File Handling Cheat Sheet
Available File Modes
| Modes | Description |
|---|---|
| r | Open a file for read only. File pointer starts at the beginning of the file |
| w | Open a file for write only. Erases the contents of the file or creates a new file if it doesn't exist. File pointer starts at the beginning of the file |
| a | Open a file for write only. The existing data in file is preserved. File pointer starts at the end of the file. Creates a new file if the file doesn't exist |
| x | Creates a new file for write only. Returns FALSE and an error if file already exists |
| r+ | Open a file for read/write. File pointer starts at the beginning of the file |
| w+ | Open a file for read/write. Erases the contents of the file or creates a new file if it doesn't exist. File pointer starts at the beginning of the file |
| a+ | Open a file for read/write. The existing data in file is preserved. File pointer starts at the end of the file. Creates a new file if the file doesn't exist |
| x+ | Creates a new file for read/write. Returns FALSE and an error if file already exists |
PERMISSIONS
If you are having problems with accessing files, a good place to start looking is at the file permissions. To learn more about file permissions, check out our Console Foundations course, specifically the video on File Permissions
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If you've taken our basic PHP course or
0:00
really done almost anything in PHP,
you've already been reading files.
0:03
They include and require statements read
additional files into the current file.
0:08
This is a great way to cut back and
rewriting the same thing all the time.
0:13
We can write things once and
include them wherever we want.
0:18
But this course is really
about giving you control.
0:22
We want to be able to do
something with those files,
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besides just dumping them
into the current file.
0:28
So, let's take a look at some of the other
options we have for reading files.
0:31
We're going to create a form,
and bring in country, and
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state drop-downs from some other files.
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If we click on the HTML countries.html,
and view the page source.
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You can see that this is
a list of drop down options.
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The other HTML files
are formatted the same way, and
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you can browse each of them if you'd like.
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Back in work spaces create a new
file name state_formed.php.
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Let's add our form tag and
then create a country drop down.
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<label for="country">Country</label> And
then, our select.
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For country, we're just going
to include our countries file.
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Let's view this in the browser.
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We can see that their
drop down is populated.
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Let's go back and add a state drop down
now using a little more control this time.
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We'll add a label for our state.
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And then our select.
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This time we'll start by reading
the file with the fopen function.
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This function opens
a connection to a file,
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and returns a file handler that we
can use to connect to the file.
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This is the same kind of thing that we do
when we set up a connection to a database.
3:00
To open a connection, we first tell it,
which file we want to open, and
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then tell it which mode we want to use.
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What are we doing with the file?
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Reading?
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Writing?
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Appending?
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Or even creating a file
if it doesn’t exist.
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Check the notes associated with
this video for mode options, and
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additional features of fopen.
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First we pass data/ html/states.html.
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And then, since we want to read the file,
we use r as the mode.
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We'll wrap this in an F statement, so
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we can perform our actions only if
we're actually able to open the file.
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We set our file handle equal to the fopen
And now, we perform our actions.
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The first action I want to add within the
statement is the action to close the file.
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Use fclose and pass the file handler,
Before I close the file.
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I want to loop over each line,
we can create any kind of loop we want.
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We could loop through only
a specific number of lines, or
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until we find a certain character.
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I want to loop through all
the lines in this file.
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So, I will use the end of file function.
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While not file, and a file,
and our file handler.
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To read each line,
we use that fgets function.
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This returns the current line as a string,
and moves the pointer to the next line.
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We can now echo that line.
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Let's preview this in the browser again.
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This time we see the state
drop down as well.
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But we haven't actually done
anything more than include the file.
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So, let's say, that I want to
default the selection to Oregon.
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Let's go back to Workspaces,
and add some additional code.
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If the string position
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of line for Oregon.
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This will check if my line
contains the string Oregon.
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If so, then I want to string replace.
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Oregon, with
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selected Oregon.
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Else, we'll echo the line.
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Let's check our browser again.
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This time Oregon is selected by default.
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We could make any comparisons, or
manipulations we wanted to this line.
6:17
But let's check out another function for
reading files.
6:21
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