问题
I was working with code that parses crontab.
https://stackoverflow.com/a/5727346/3774582
I found it works great, however I found that if I made a cron like
0 * * * *
It would run at the 0 minute, the 8th minute, and the 9th minute. I broke down every line of the code.
https://gist.github.com/goosehub/7deff7928be04ec99b4292be10b4b7b0
I found that I was getting this conditional for the value of 0 if the current minute was 8.
08 === 0
I tested this with PHP
if (08 === 0) {
echo 'marco';
}
After running that, I saw marco on the output. It appears PHP is treating 08 as an octal. Because in octal after 07 is 010, 08 and 09 is evaluated as 00.
How can I force a decimal comparison in this conditional?
回答1:
From the PHP docs in Integer
http://php.net/manual/en/language.types.integer.php
To use octal notation, precede the number with a 0 (zero).
However, don't just use ltrim($time[$k], '0') because this will turn 0 into . Instead, use a regular expression. In this case, /^0+(?=\d)/.
In this case, apply it to the $time[$k] input like so.
$time[$k] = preg_replace('/^0+(?=\d)/', '', $time[$k]);
来源：https://stackoverflow.com/questions/41383406/how-to-prevent-php-from-doing-octal-math-in-conditionals-why-does-08-0