string - Performance of variable expansion vs. sprintf in PHP

Question

Regarding performance, is there any difference between doing:

$message = "The request $request has $n errors";

and

$message = sprintf('The request %s has %d errors', $request, $n);

in PHP?

I would say that calling a function involves more stuff, but I do not know what's PHP doing behind the scenes to expand variables names.

Thanks!

Answer 1

It does not matter.

Any performance gain would be so minuscule that you would see it (as an improvement in the hundreths of seconds) only with 10000s or 100000s of iterations - if even then.

For specific numbers, see this benchmark. You can see it has to generate 1MB+ of data using 100,000 function calls to achieve a measurable difference in the hundreds of milliseconds. Hardly a real-life situation. Even the slowest method ("sprintf() with positional params") takes only 0.00456 milliseconds vs. 0.00282 milliseconds with the fastest. For any operation requiring 100,000 string output calls, you will have other factors (network traffic, for example) that will be an order of magniture slower than the 100ms you may be able to save by optimizing this.

Use whatever makes your code most readable and maintainable for you and others. To me personally, the sprintf() method is a neat idea - I have to think about starting to use that myself.