问题
I am trying this out, but am unable to store large value
$var = rand(100000000000000,999999999999999);
echo $var; // prints a 9 digit value(largest possible)
How to get a desired value ?
回答1:
PHP ints are typically 32 bits. Other packages provide higher-precision ints: http://php.net/manual/en/language.types.integer.php
回答2:
From the manual:
The size of an integer is platform-dependent, although a maximum value of about two billion is the usual value (that's 32 bits signed). 64-bit platforms usually have a maximum value of about 9E18. PHP does not support unsigned integers. Integer size can be determined using the constant PHP_INT_SIZE, and maximum value using the constant PHP_INT_MAX since PHP 4.4.0 and PHP 5.0.5.
...
If PHP encounters a number beyond the bounds of the integer type, it will be interpreted as a float instead. Also, an operation which results in a number beyond the bounds of the integer type will return a float instead.
BC Math and GMP are the (only?) way to manipulate this limitation.
回答3:
If you need to work with very large numbers I have found success with BC Math. Here is a link to everything you need to know:
http://php.net/manual/en/book.bc.php
回答4:
If you want to generate the number and manipulate as a native type, you can't with most PHP installations (either you have 32 or 64 bit ints and nothing else), as the other answers have already stated. However, if you are just generating a number and want to pass it around a possible trick is to just concatenate strings:
$var = rand(0,PHP_INT_MAX).str_pad(rand(0, 999999999), 9, 0, STR_PAD_LEFT);
echo $var;
On a platform in which PHP uses a 32 bit integer, this allows you to get a near random integer (as a string) that is bigger than 32 bits ( > 10 decimal places). Of course, there is a bias in this construction which means you won't cover all the numbers with the same probability. The limits of the rand() calls obey normal decimal rules so its simple to adjust the upper bound of the number you want.
If all you're doing is storing/transmitting/showing this value, the string will be just fine. Equality and greater/less than tests will also work. Just don't do any math with it.
来源：https://stackoverflow.com/questions/8647125/using-long-int-in-php