php - file read

php - file read

My apologies for taking so long to actually get to the point where you get information from files. In this lesson we will teach you how to read data from a file using various PHP functions.

php - file open: read

Before we can read information from a file we have to use the function fopen to open the file for reading. Here's the code to read-open the file we created in the PHP File Write lessons.

PHP Code:

$myFile = "testFile.txt";

$fh = fopen($myFile, 'r');

The file we created in the last lesson was named "testFile.txt". Your PHP script that you are writing should reside in the same directory as "text.txt". Here are the contents of our file from File Write.

php - file read: fread function

The fread function is the staple for getting data out of a file. The function requires a file handle, which we have, and an integer to tell the function how much data, in bytes, it is supposed to read.

One character is equal to one byte. If you wanted to read the first five characters then you would use five as the integer.

PHP Code:

$myFile = "testFile.txt";

$fh = fopen($myFile, 'r');

$theData = fread($fh, 5);

fclose($fh);

echo $theData;

The first five characters from the testFile.txt file are now stored inside $theData. You could echo this string, $theData, or write it to another file.

If you wanted to read all the data from the file, then you need to get the size of the file. The filesize function returns the length of a file, in bytes, which is just what we need! The filesize function requires the name of the file that is to be sized up.

PHP Code:

$myFile = "testFile.txt";

$fh = fopen($myFile, 'r');

$theData = fread($fh, filesize($myFile));

fclose($fh);

echo $theData;

php - file read: gets function

PHP also lets you read a line of data at a time from a file with the gets function. This can or cannot be useful to you, the programmer. If you had separated your data with new lines then you could read in one segment of data at a time with the gets function.

Lucky for us our "testFile.txt" file is separated by new lines and we can utilize this function.

PHP Code:

$myFile = "testFile.txt";

$fh = fopen($myFile, 'r');

$theData = fgets($fh);

fclose($fh);

echo $theData;