Any difference between print() and readfile() when loading an image file? - php

Question

Just wondering if there is any difference with the two below code examples:
$image = 'http://www.example.com/image.jpg'
$photo = file_get_contents($image);
ob_start();
header("Content-type: image/jpeg");
print($photo);
ob_end_flush();
or...
$image = 'http://www.example.com/image.jpg'
$photo = file_get_contents($image);
ob_start();
header("Content-type: image/jpeg");
readfile($photo);
ob_end_flush();

Answer 1

readfile's parameter is a filename, not the content itself. Therefore, you'd call it like this:
$image = 'http://www.example.com/image.jpg'
ob_start();
header("Content-type: image/jpeg");
readfile($image);
ob_end_flush();
Since readfile reads and write chunks at a time, its memory consumption will be constant, whereas when you store the result of file_get_contents into $photo, you'll need to have enough memory to store the image.
In your case, the output buffering makes the file_get_contents variant demand twice as much memory as the image's size. For a large image, readfile therefore halves the memory requirements. Note that your output buffering means that the download will be delayed. If you don't need it for anything else, you will get better performance (both in actual speed and server memory requirements) if you simply disable it:
$image = 'http://www.example.com/image.jpg'
header("Content-type: image/jpeg");
if (#readfile($image) === false) {
// print error image
}

Answer 2

There is a very significant difference in that readfile takes the filename as the argument.
The second snippet should be something like
$image = ...
readfile($image)
This has the advantage of not having to store the entire file contents in memory (a string) since readfile emits it immediately. Of course, if you buffer the output that is no longer true.

Answer 3

In the first instance your code would never work
readfile($photo);
^--------------- Takes file name not string
PHP DOC SAYS
Reads a file and writes it to the output buffer.
You don't need to re event that and duplicate that with multiple other functions its just saying
readfile = file_get_contents + print
It just like using fopen instead of file_get_contents just a get a simple content in a file
Lastly readfile is faster tested with 10000 loop on same image
Single Run
Array
(
[m1] => 0.0006101131439209
[m2] => 0.00031208992004395
)
Dual Run
Array
(
[m1] => 3.4585757255554
[m2] => 2.9963381290436 <---- Faster
)
m1 & m2 functions
function m1($array) {
$photo = file_get_contents('a.png');
ob_start();
print($photo);
ob_end_clean();
}
// Array clean copy
function m2($array) {
ob_start();
readfile('a.png');
ob_end_clean();
}