PHP - Example 6

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Example 6 - Reading From a File

The previous example illustrated how to use PHP to read form data. In many cases you will also want to store the information submitted in a file or database. For example, if you are conducting an online survey you would want to write the survey results to a file so you an analyze them later. This example reads the output.txt created in the previous example and writes the information to the browser window.

<HTML>
<HEAD>
<TITLE> Example 6 </TITLE>
</HEAD>
<BODY>

<?  

// the following statement opens the files called output.txt
// and reads each line of the file into an array called $readfile

// Each line will be accessed by it's position in the array
// $readfile[0] would be the first line because the array begins at 0
// rather than 1

$readfile = file("output.txt");

// Create a loop that will read all elements of the array and print out
// each field of the tab-delimited text file

for ($k=0; $k<=count($readfile)-1; $k++) {
    $fields = split("\t",$readfile[$k]);
    print("$fields[0] $fields[2]<br>");
}


?>


</BODY>
</HTML>

There are several functions used to read data in PHP. This example uses the file function, which reads each line of the specified file into an array. The $readfile array in the example is a collection of values. To access a particular element of the array use $arrayname[N] where N is the number of the element you want to access. PHP numbers arrays beginning at 0 so to read the second element of the $readfile array use $readfile[1].

Next, the Example uses a for loop to process all of the elements of the array. The syntax of a for loop is:

for ($var=start value; $var< stop value; increment) {
   statements to perform;
}

The $var variable will take a different value each time through the loop. The loop will repeat as long as $var is less than the specified stop value.

Within the loop the PHP split function is used to parse each line of the file. Since the output.txt file created in Example 5 is tab-delimited, the split function splits the line on the tab character and stores each element in the array called $fields.

Finally, the print statement prints the desired fields to the browser.

Note for UT Austin Web Central Users: Because Web Central runs PHP in safe mode, the file that you read from must be owned by the same user that owns the PHP script. If you have questions about this, we suggest making an appointment with a Teamweb consultant.

Test Example 6

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Simple Search

Example 6 can easily be modified to search for a particular record in a file rather than simply displaying all records. Add a conditional statement within the for loop to check if the field that was just read matches some condition, for example a search string entered in a form.


for ($k=0; $k<=count($readfile)-1; $k++) {
    $fields = split("\t",$readfile[$k]);

    // if the name field equals the name field entered in a search form
    // print that record and exit the loop

    if ($fields[0] == htmlentities($_POST[searchname])) {

       print("$fields[0] and $fields[2]<br>");
       exit;
     }
}

Test this search example

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Example 6 - Reading From a File

Simple Search