Question

i’m very confused here.

How can I loop this:

start from 0-9a-zA-Z

foreach alphanumeric char from the above range, I have to create a string

the very fist string will be

0000
... ( thousands of string generated between)
0009
... ( thousands of string generated between)
000a
... ( thousands of string generated between)
000z
000A
... ( thousands of string generated between)
000Z
.... ( thousands of string generated between)
ZZZA
... ( thousands of string generated between)
ZZZZ

Answer 1

Here is one solution:

$corpus = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
for( $i = 0; $i < strlen($corpus); $i++ )
   for( $j = 0; $j < strlen($corpus); $j++ )
      for( $k = 0; $k < strlen($corpus); $k++ )
         for( $l = 0; $l < strlen($corpus); $l++ )
              print substr($corpus, $i, 1).substr($corpus, $j, 1).substr($corpus, $k, 1).substr($corpus, $l, 1)."\n";