Generate SSCC-18 barcode & verify SSCC-18 check digit

SSCC-18.php

<?php

/**
 * Generate and return an SSCC-18 barcode. DOES NOT include leading "00"
 * Params can be passed as strings or ints and will be padded to proper length.
 * @param string $next_serial_available
 * @param string $extension 
 * @param string $gs1_prefix
 * @param string $min_serial
 * @param string $max_serial
 * @return string 18 digit Barcode or NULL on error.
 */
public static function generate_sscc_barcode($next_serial_available, $extension, $gs1_prefix, $min_serial, $max_serial){
  // Some basic sanity checks
  if(!is_numeric($next_serial_available) || !is_numeric($gs1_prefix) || !is_numeric($min_serial) || !is_numeric($max_serial)){
    return null;
  }
  if($max_serial > 999999999){
    $max_serial = 999999999;
  }

  // Alternatively figure out next available serial number here. Make sure transaction is atomic.
  $serial = $next_serial_available;

  // Make sure extension digit is valid. Otherwise set it to 0
  if(empty($extension) || strlen($extension) !== 1 || !preg_match('/[0-9]/', $extension)){
    $extension = '0';
  }

  $barcode = $extension.str_pad($gs1_prefix, 7, '0', STR_PAD_LEFT).str_pad($serial, 9, '0', STR_PAD_LEFT);
  $check_digit = sscc_check_digit($barcode);
  // If we couldn't generate check digit, return null
  if($check_digit === false){
    return null;
  }

  return "$barcode$check_digit";
}

/**
 * Given a sscc barcode w/ or w/o final check digit will either return check digit if missing or TRUE/FALSE if digit does/doesn't match or formatting is incorrect.
 * @param string $barcode
 * @return mixed Returns true/false if existing check digit is correct. Returns check digit if it's missing from the barcode.
 */
function sscc_check_digit($barcode){
  // Strip off leading 0's if 20 digit format was provided
  $len = strlen($barcode);
  if (($len == 20  || $len == 19) && strpos($barcode, '00') === 0){
    $barcode = substr($barcode, 2);
  }
  // Return false if invalid length
  $len = strlen($barcode);
  if ($len != 18 && $len != 17){
    return false;
  }

  // For explanation see: http://www.gs1.org/how-calculate-check-digit-manually
  $sum = 0;
  for($i=0; $i<17; $i++){
    $multiplier = ($i % 2 == 0) ? 3 : 1;

    $sum += intval($barcode{$i}) * $multiplier;
  }
  $check_digit = (ceil($sum / 10) * 10) - $sum;

  if($len == 17){
    return "$check_digit";
  }
  if($len == 18){
    return ($check_digit == intval($barcode{17}));
  }
}

Hi JaggedJax, i cannot find a lot PHP resources about SSCC-18, i need to create images of a SSCC-18 in PHP, do you know where can i found something about this? Thanks.

Hi JaggedJax, i cannot find a lot PHP resources about SSCC-18, i need to create images of a SSCC-18 in PHP, do you know where can i found something about this? Thanks.

You can use the library at https://github.com/picqer/php-barcode-generator to do that