PHP - To echo or not to echo?

Question

What is more efficient and/or what is better practice, to echo the HTML or have many open and close php tags?

Obviously for big areas of HTML it is sensible

Answer 1

echo sends its argument further down the request processing chain, and eventually this string is sent to the client through a say, network socket. Depending on how the echo works in conjunction with underlying software layers (e.g. webserver), sometimes your script may be able to execute faster than it can push data to the client. Without output buffering, that is. With output buffering, you trade memory to gain speed - you echos are faster because they accumulate in a memory buffer. But only if there is no implicit buffering going on. One'll have to inspect Apache source code to see how does it treat PHPs stdout data.

That said, anything below is true for output buffering enabled scripts only, since without it the more data you attempt to push at once the longer you have to wait (the client has to receive and acknowledge it, by ways of TCP!).

It is more efficient to send a large string at once than do N echos concatenating output. By similar logic, it is more efficient for the interpreter to enter the PHP code block (PHP processing instruction in SGML/XML markup) once than enter and exit it many times.

As for me, I assemble my markup not with echo, but using XML DOM API. This is also in accordance with the article linked above. (I reprint the link: http://hsivonen.iki.fi/producing-xml/) This also answers the question whether to use one or many PHP tags. Use one tag which is your entire script, let it assemble the resulting markup and send it to the client.