How to get a random number with four letters and numbers in PHP (verification code)

This article mainly introduces the process of PHP program development. We often make some four-digit verification codes on the login interface or comment interface. Friends who need it can refer to it

So we know that simple four-digit pure number verification in php can use rand(1000,9999), but if we want to get a random four-digit number of letters and numbers, then how should we write What about function? 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 parameters min and max are not provided, mt_rand() returns a pseudo-random number between 0 and RAND_MAX. For example, if you want a random number between 0 and 46 (inclusive), use mt_rand(0, 46).

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