正如我在另一个问题中解释的逻辑，我自己创建了一个函数。根据维基百科文章中解释的逻辑，在下面找到一个合适的函数。国家特定验证。
每个国家/地区的算法和字符长度见https://en.wikipedia.org/wiki/International_Bank_Account_Number#Validating_the_IBAN。

function checkIBAN($iban)
{
    if(strlen($iban) < 5) return false;
    $iban = strtolower(str_replace(' ','',$iban));
    $Countries = array('al'=>28,'ad'=>24,'at'=>20,'az'=>28,'bh'=>22,'be'=>16,'ba'=>20,'br'=>29,'bg'=>22,'cr'=>21,'hr'=>21,'cy'=>28,'cz'=>24,'dk'=>18,'do'=>28,'ee'=>20,'fo'=>18,'fi'=>18,'fr'=>27,'ge'=>22,'de'=>22,'gi'=>23,'gr'=>27,'gl'=>18,'gt'=>28,'hu'=>28,'is'=>26,'ie'=>22,'il'=>23,'it'=>27,'jo'=>30,'kz'=>20,'kw'=>30,'lv'=>21,'lb'=>28,'li'=>21,'lt'=>20,'lu'=>20,'mk'=>19,'mt'=>31,'mr'=>27,'mu'=>30,'mc'=>27,'md'=>24,'me'=>22,'nl'=>18,'no'=>15,'pk'=>24,'ps'=>29,'pl'=>28,'pt'=>25,'qa'=>29,'ro'=>24,'sm'=>27,'sa'=>24,'rs'=>22,'sk'=>24,'si'=>19,'es'=>24,'se'=>24,'ch'=>21,'tn'=>24,'tr'=>26,'ae'=>23,'gb'=>22,'vg'=>24);
    $Chars = array('a'=>10,'b'=>11,'c'=>12,'d'=>13,'e'=>14,'f'=>15,'g'=>16,'h'=>17,'i'=>18,'j'=>19,'k'=>20,'l'=>21,'m'=>22,'n'=>23,'o'=>24,'p'=>25,'q'=>26,'r'=>27,'s'=>28,'t'=>29,'u'=>30,'v'=>31,'w'=>32,'x'=>33,'y'=>34,'z'=>35);

    if(array_key_exists(substr($iban,0,2), $Countries) && strlen($iban) == $Countries[substr($iban,0,2)]){
                
        $MovedChar = substr($iban, 4).substr($iban,0,4);
        $MovedCharArray = str_split($MovedChar);
        $NewString = "";

        foreach($MovedCharArray AS $key => $value){
            if(!is_numeric($MovedCharArray[$key])){
                if(!isset($Chars[$MovedCharArray[$key]])) return false;
                $MovedCharArray[$key] = $Chars[$MovedCharArray[$key]];
            }
            $NewString .= $MovedCharArray[$key];
        }
        
        if(bcmod($NewString, '97') == 1)
        {
            return true;
        }
    }
    return false;
}

对@PeterFox答案进行了轻微修改，包括在bcmath不可用时支持bcmod()，

<?php

function isValidIBAN ($iban) {

  $iban = strtolower($iban);
  $Countries = array(
    'al'=>28,'ad'=>24,'at'=>20,'az'=>28,'bh'=>22,'be'=>16,'ba'=>20,'br'=>29,'bg'=>22,'cr'=>21,'hr'=>21,'cy'=>28,'cz'=>24,
    'dk'=>18,'do'=>28,'ee'=>20,'fo'=>18,'fi'=>18,'fr'=>27,'ge'=>22,'de'=>22,'gi'=>23,'gr'=>27,'gl'=>18,'gt'=>28,'hu'=>28,
    'is'=>26,'ie'=>22,'il'=>23,'it'=>27,'jo'=>30,'kz'=>20,'kw'=>30,'lv'=>21,'lb'=>28,'li'=>21,'lt'=>20,'lu'=>20,'mk'=>19,
    'mt'=>31,'mr'=>27,'mu'=>30,'mc'=>27,'md'=>24,'me'=>22,'nl'=>18,'no'=>15,'pk'=>24,'ps'=>29,'pl'=>28,'pt'=>25,'qa'=>29,
    'ro'=>24,'sm'=>27,'sa'=>24,'rs'=>22,'sk'=>24,'si'=>19,'es'=>24,'se'=>24,'ch'=>21,'tn'=>24,'tr'=>26,'ae'=>23,'gb'=>22,'vg'=>24
  );
  $Chars = array(
    'a'=>10,'b'=>11,'c'=>12,'d'=>13,'e'=>14,'f'=>15,'g'=>16,'h'=>17,'i'=>18,'j'=>19,'k'=>20,'l'=>21,'m'=>22,
    'n'=>23,'o'=>24,'p'=>25,'q'=>26,'r'=>27,'s'=>28,'t'=>29,'u'=>30,'v'=>31,'w'=>32,'x'=>33,'y'=>34,'z'=>35
  );

  if (strlen($iban) != $Countries[ substr($iban,0,2) ]) { return false; }

  $MovedChar = substr($iban, 4) . substr($iban,0,4);
  $MovedCharArray = str_split($MovedChar);
  $NewString = "";

  foreach ($MovedCharArray as $k => $v) {

    if ( !is_numeric($MovedCharArray[$k]) ) {
      $MovedCharArray[$k] = $Chars[$MovedCharArray[$k]];
    }
    $NewString .= $MovedCharArray[$k];
  }
  if (function_exists("bcmod")) { return bcmod($NewString, '97') == 1; }

  // http://au2.php.net/manual/en/function.bcmod.php#38474
  $x = $NewString; $y = "97";
  $take = 5; $mod = "";

  do {
    $a = (int)$mod . substr($x, 0, $take);
    $x = substr($x, $take);
    $mod = $a % $y;
  }
  while (strlen($x));

  return (int)$mod == 1;
}

接受的答案不是首选的验证方式。specification表示以下内容：
1.检查IBAN总长度是否正确（根据国家）。否则，IBAN无效
1.将两个校验位替换为00（例如GB 00（英国）
1.将四个初始字符移到字符串的末尾
1.将字符串中的字母替换为数字，根据需要扩展字符串，例如A或a = 10，B或b = 11，Z或z = 35。因此，每个字母字符都被2个数字替换
1.将字符串转换为整数（即忽略前导零）
1.计算新数的mod-97，结果为余数
1.从98中减去余数，并将结果用于两个校验位。如果结果是一个个位数，用前导0填充它，使其成为一个两位数
我已经编写了一个类，它根据规范验证、格式化和解析字符串。希望这能帮助一些保存自己滚动所需的时间。
代码可以在GitHub here上找到。

顶级功能不工作。
只要尝试一个字符串与'%'在它...
我用这个：

function checkIBAN($iban) {

// Normalize input (remove spaces and make upcase)
$iban = strtoupper(str_replace(' ', '', $iban));

if (preg_match('/^[A-Z]{2}[0-9]{2}[A-Z0-9]{1,30}$/', $iban)) {
    $country = substr($iban, 0, 2);
    $check = intval(substr($iban, 2, 2));
    $account = substr($iban, 4);

    // To numeric representation
    $search = range('A','Z');
    foreach (range(10,35) as $tmp)
        $replace[]=strval($tmp);
    $numstr=str_replace($search, $replace, $account.$country.'00');

    // Calculate checksum
    $checksum = intval(substr($numstr, 0, 1));
    for ($pos = 1; $pos < strlen($numstr); $pos++) {
        $checksum *= 10;
        $checksum += intval(substr($numstr, $pos,1));
        $checksum %= 97;
    }

    return ((98-$checksum) == $check);
} else
    return false;
}

我在cakephp 3.7 validation class中找到了这个解决方案。简单漂亮的php实现。

/**
 * Check that the input value has a valid International Bank Account Number IBAN syntax
 * Requirements are uppercase, no whitespaces, max length 34, country code and checksum exist at right spots,
 * body matches against checksum via Mod97-10 algorithm
 *
 * @param string $check The value to check
 *
 * @return bool Success
 */
public static function iban($check)
{
    if (!preg_match('/^[A-Z]{2}[0-9]{2}[A-Z0-9]{1,30}$/', $check)) {
        return false;
    }

    $country = substr($check, 0, 2);
    $checkInt = intval(substr($check, 2, 2));
    $account = substr($check, 4);
    $search = range('A', 'Z');
    $replace = [];
    foreach (range(10, 35) as $tmp) {
        $replace[] = strval($tmp);
    }
    $numStr = str_replace($search, $replace, $account . $country . '00');
    $checksum = intval(substr($numStr, 0, 1));
    $numStrLength = strlen($numStr);
    for ($pos = 1; $pos < $numStrLength; $pos++) {
        $checksum *= 10;
        $checksum += intval(substr($numStr, $pos, 1));
        $checksum %= 97;
    }

    return ((98 - $checksum) === $checkInt);
}

此功能检查IBAN，需要GMP激活http://php.net/manual/en/book.gmp.php。

function checkIban($string){
    $to_check = substr($string, 4).substr($string, 0,4);
    $converted = '';
    for ($i = 0; $i < strlen($to_check); $i++){
        $char = strtoupper($to_check[$i]);
        if(preg_match('/[0-9A-Z]/',$char)){
            if(!preg_match('/\d/',$char)){
                $char = ord($char)-55;
            }
            $converted .= $char;
        }
    }

    // prevent: "gmp_mod() $num1 is not an integer string" error
    $converted = ltrim($converted, '0');

    return strlen($converted) && gmp_strval(gmp_mod($converted, '97')) == 1;
}

好好享受吧！

我建议对校验和计算进行一些优化

function calculateIBANChecksum($CIBAN){
$CX = str_split($CIBAN);
$checksum = $CX[0];
array_shift($CX);
foreach ($CX as $pos => $DIGIT) {
    $checksum *= 10;
    $checksum += $DIGIT * 1;
    $checksum %= 97;
}
return  (98 - $checksum);

}