- Using Text Within date()
- Automatically Localizing Dates
- Manually Localizing Dates
- Using the Current Date the U.S./U.K./European Way
- Formatting a Specific Date
- Validating a Date
- Calculating a Relative Date
- Creating a Sortable Time Stamp
- Converting a String into a Date
- Determining Sunrise and Sunset
- Using Date and Time for Benchmarks
- Using Form Fields for Date Selection
- Create Self-updating Form Fields for Date Selection
- Calculating the Difference Between Two Dates
- Using GMT Date/Time Information
This chapter is from the book
This chapter is from the book
This chapter is from the book
Using Date and Time for Benchmarks
$start = microtimestamp(); $end = microtimestamp(); ($end-$start)
Up to now, all date/time functions did not produce results that were more precise than on the second level; no microseconds were available. This changes when you use the function gettimeofday(). This returns an array of values. The key ‘sec’ returns the associated epoche value; however, ‘usec’ returns the additional microseconds. With this, a very exact value can be used for operations that need exact measurement, for example, benchmarks.
<?php
// ...
$start = microtimestamp();
$s = ‘‘;
for ($i=0; $i < 100000; $i++) {
$s .= "$i";
}
$end = microtimestamp();
echo ‘Using double quotes: ‘ . ($end-$start) .
‘<br />‘;
$start = microtimestamp();
$s = ‘‘;
for ($i=0; $i < 100000; $i++) {
$s .= $i;
}
$end = microtimestamp();
echo ‘Using no quotes: ‘ . ($end-$start) . ‘<br
/>‘;
?>
Benchmarking Code Using microtimestamp() (benchmark.php; excerpt)
The code at the beginning of this phrase contains a function microtimestamp() that returns an exact time stamp. This function is called twice; in between, a more or less complex calculation is done. The result of this is a benchmark that might help decide which coding technique is superior.
function microtimestamp() {
$timeofday = gettimeofday();
return $timeofday[‘sec‘] + $timeofday[‘usec‘] /
1000000;
}
Figure 3.3 shows the result. Your mileage might vary, but you will find that using the double quotes just costs time. (In another experiment, you might also find out that it makes no difference whether you use single or double quotes—despite popular beliefs.)
)
Figure 3.3 The second piece of code is the faster one.