So we know that simple four-digit pure number verification in php can be done with rand(1000,9999), but if we want to get random four-digit numbers of letters and numbers, then how should we write a function Woolen cloth? Hu Peng's blog below gives a complete example under the PHP information column.
<?php function GetfourStr($len) { $chars_array = array( "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", ); $charsLen = count($chars_array) - 1; $outputstr = ""; for ($i=0; $i<$len; $i++) { $outputstr .= $chars_array[mt_rand(0, $charsLen)]; } return $outputstr; } echo GetfourStr(4); ?>
Part of the function analysis: mt_rand function description: mt_rand() returns a random integer.
If the optional min and max arguments are not provided, mt_rand() returns a pseudorandom number between 0 and RAND_MAX. For example, if you want a random number between 0 and 46 (inclusive), use mt_rand(0, 46).