Specifications

It is not generally sensible to read a file character-by-character unless for some reason we want

to process it character-by-character.

Reading an Arbitrary Length: fread()

The final way we can read from a file is using the fread() function to read an arbitrary num-

ber of bytes from the file. This function has the following prototype:

string fread(int fp, int length);

The way it works is to read up to length bytes or to the end of file, whichever comes first.

Other Useful File Functions

There are a number of other file functions we can use that are useful from time-to-time.

Checking Whether a File Is There: file_exists()

If you want to check if a file exists without actually opening it, you can use file_exists(),as

follows:

if (file_exists(“$DOCUMENT_ROOT/../orders/orders.txt”))

echo “There are orders waiting to be processed.”;

else

echo “There are currently no orders.”;

Knowing How Big a File Is: filesize()

You can check the size of a file with the filesize() function. It returns the size of a file in

bytes:

echo filesize(“$DOCUMENT_ROOT/../orders/orders.txt”);

It can be used in conjunction with fread() to read a whole file (or some fraction of the file) at

a time. We can replace our entire original script with

$fp = fopen(“$DOCUMENT_ROOT/../orders/orders.txt”, “r”);

echo fread( $fp, filesize(“$DOCUMENT_ROOT/../orders/orders.txt” ));

fclose( $fp );

Deleting a File: unlink()

If you want to delete the order file after the orders have been processed, you can do it using

unlink(). (There is no function called delete.) For example

unlink(“$DOCUMENT_ROOT/../orders/orders.txt”);

This function returns false if the file could not be deleted. This will typically occur if the per-

missions on the file are insufficient or if the file does not exist.

Storing and Retrieving Data

HAPTER 2

STORING AND

RETRIEVING DATA

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