试试kotlin。添加Regex并添加到when语句中。

private fun getCardType(number: String): String {

        val visa = Regex("^4[0-9]{12}(?:[0-9]{3})?$")
        val mastercard = Regex("^5[1-5][0-9]{14}$")
        val amx = Regex("^3[47][0-9]{13}$")

        return when {
            visa.matches(number) -> "Visa"
            mastercard.matches(number) -> "Mastercard"
            amx.matches(number) -> "American Express"
            else -> "Unknown"
        }
    }

public string GetCreditCardType(string CreditCardNumber)
{
    Regex regVisa = new Regex("^4[0-9]{12}(?:[0-9]{3})?$");
    Regex regMaster = new Regex("^5[1-5][0-9]{14}$");
    Regex regExpress = new Regex("^3[47][0-9]{13}$");
    Regex regDiners = new Regex("^3(?:0[0-5]|[68][0-9])[0-9]{11}$");
    Regex regDiscover = new Regex("^6(?:011|5[0-9]{2})[0-9]{12}$");
    Regex regJCB = new Regex("^(?:2131|1800|35\\d{3})\\d{11}$");


    if (regVisa.IsMatch(CreditCardNumber))
        return "VISA";
    else if (regMaster.IsMatch(CreditCardNumber))
        return "MASTER";
    else  if (regExpress.IsMatch(CreditCardNumber))
        return "AEXPRESS";
    else if (regDiners.IsMatch(CreditCardNumber))
        return "DINERS";
    else if (regDiscover.IsMatch(CreditCardNumber))
        return "DISCOVERS";
    else if (regJCB.IsMatch(CreditCardNumber))
        return "JCB";
    else
        return "invalid";
}

下面是使用Regex, c#检查信用卡类型的函数

这是一个php类函数，通过CCnumber返回CCtype。 此代码不验证卡或不运行Luhn算法仅尝试查找基于本页表的信用卡类型。基本上使用CCnumber长度和CCcard前缀来确定CCcard类型。

<?php
class CreditcardType
{
    public static $creditcardTypes = [
        [
            'Name' => 'American Express',
            'cardLength' => [15],
            'cardPrefix' => ['34', '37'],
        ], [
            'Name' => 'Maestro',
            'cardLength' => [12, 13, 14, 15, 16, 17, 18, 19],
            'cardPrefix' => ['5018', '5020', '5038', '6304', '6759', '6761', '6763'],
        ], [
            'Name' => 'Mastercard',
            'cardLength' => [16],
            'cardPrefix' => ['51', '52', '53', '54', '55'],
        ], [
            'Name' => 'Visa',
            'cardLength' => [13, 16],
            'cardPrefix' => ['4'],
        ], [
            'Name' => 'JCB',
            'cardLength' => [16],
            'cardPrefix' => ['3528', '3529', '353', '354', '355', '356', '357', '358'],
        ], [
            'Name' => 'Discover',
            'cardLength' => [16],
            'cardPrefix' => ['6011', '622126', '622127', '622128', '622129', '62213','62214', '62215', '62216', '62217', '62218', '62219','6222', '6223', '6224', '6225', '6226', '6227', '6228','62290', '62291', '622920', '622921', '622922', '622923','622924', '622925', '644', '645', '646', '647', '648','649', '65'],
        ], [
            'Name' => 'Solo',
            'cardLength' => [16, 18, 19],
            'cardPrefix' => ['6334', '6767'],
        ], [
            'Name' => 'Unionpay',
            'cardLength' => [16, 17, 18, 19],
            'cardPrefix' => ['622126', '622127', '622128', '622129', '62213', '62214','62215', '62216', '62217', '62218', '62219', '6222', '6223','6224', '6225', '6226', '6227', '6228', '62290', '62291','622920', '622921', '622922', '622923', '622924', '622925'],
        ], [
            'Name' => 'Diners Club',
            'cardLength' => [14],
            'cardPrefix' => ['300', '301', '302', '303', '304', '305', '36'],
        ], [
            'Name' => 'Diners Club US',
            'cardLength' => [16],
            'cardPrefix' => ['54', '55'],
        ], [
            'Name' => 'Diners Club Carte Blanche',
            'cardLength' => [14],
            'cardPrefix' => ['300', '305'],
        ], [
            'Name' => 'Laser',
            'cardLength' => [16, 17, 18, 19],
            'cardPrefix' => ['6304', '6706', '6771', '6709'],
        ],
    ];

    public static function getType($CCNumber)
    {
        $CCNumber = trim($CCNumber);
        $type = 'Unknown';
        foreach (CreditcardType::$creditcardTypes as $card) {
            if (! in_array(strlen($CCNumber), $card['cardLength'])) {
                continue;
            }
            $prefixes = '/^(' . implode('|', $card['cardPrefix']) . ')/';
            if (preg_match($prefixes, $CCNumber) == 1) {
                $type = $card['Name'];
                break;
            }
        }
        return $type;
    }
}

匹配对应卡供应商的正则表达式规则:

(4\d{12}(?:\d{3})?) (5[1-5]\d{14}) (3[47]\d{13})为美国运通。 ((?: 5020 | 5038 | 6304 | 6579 | 6761) \ d {12} (?: \ \ d) ?)大师。 (3(?:0[0-5]|[68][0-9])[0-9]{11}) (6(?:011|5[0-9]{2})[0-9]{12})用于发现。 (35[2-8][89]\d\d\d{10})

Usman Y回答的Swift 2.1版本。 使用print语句来验证，因此调用某个字符串值

print(self.validateCardType(self.creditCardField.text!))

func validateCardType(testCard: String) -> String {

    let regVisa = "^4[0-9]{12}(?:[0-9]{3})?$"
    let regMaster = "^5[1-5][0-9]{14}$"
    let regExpress = "^3[47][0-9]{13}$"
    let regDiners = "^3(?:0[0-5]|[68][0-9])[0-9]{11}$"
    let regDiscover = "^6(?:011|5[0-9]{2})[0-9]{12}$"
    let regJCB = "^(?:2131|1800|35\\d{3})\\d{11}$"


    let regVisaTest = NSPredicate(format: "SELF MATCHES %@", regVisa)
    let regMasterTest = NSPredicate(format: "SELF MATCHES %@", regMaster)
    let regExpressTest = NSPredicate(format: "SELF MATCHES %@", regExpress)
    let regDinersTest = NSPredicate(format: "SELF MATCHES %@", regDiners)
    let regDiscoverTest = NSPredicate(format: "SELF MATCHES %@", regDiscover)
    let regJCBTest = NSPredicate(format: "SELF MATCHES %@", regJCB)


    if regVisaTest.evaluateWithObject(testCard){
        return "Visa"
    }
    else if regMasterTest.evaluateWithObject(testCard){
        return "MasterCard"
    }

    else if regExpressTest.evaluateWithObject(testCard){
        return "American Express"
    }

    else if regDinersTest.evaluateWithObject(testCard){
        return "Diners Club"
    }

    else if regDiscoverTest.evaluateWithObject(testCard){
        return "Discover"
    }

    else if regJCBTest.evaluateWithObject(testCard){
        return "JCB"
    }

    return ""

}

看看这个:

http://www.breakingpar.com/bkp/home.nsf/0/87256B280015193F87256CC70060A01B

function isValidCreditCard(type, ccnum) {
    /* Visa: length 16, prefix 4, dashes optional.
    Mastercard: length 16, prefix 51-55, dashes optional.
    Discover: length 16, prefix 6011, dashes optional.
    American Express: length 15, prefix 34 or 37.
    Diners: length 14, prefix 30, 36, or 38. */

    var re = new Regex({
        "visa": "/^4\d{3}-?\d{4}-?\d{4}-?\d",
        "mc": "/^5[1-5]\d{2}-?\d{4}-?\d{4}-?\d{4}$/",
        "disc": "/^6011-?\d{4}-?\d{4}-?\d{4}$/",
        "amex": "/^3[47]\d{13}$/",
        "diners": "/^3[068]\d{12}$/"
    }[type.toLowerCase()])

    if (!re.test(ccnum)) return false;
    // Remove all dashes for the checksum checks to eliminate negative numbers
    ccnum = ccnum.split("-").join("");
    // Checksum ("Mod 10")
    // Add even digits in even length strings or odd digits in odd length strings.
    var checksum = 0;
    for (var i = (2 - (ccnum.length % 2)); i <= ccnum.length; i += 2) {
        checksum += parseInt(ccnum.charAt(i - 1));
    }
    // Analyze odd digits in even length strings or even digits in odd length strings.
    for (var i = (ccnum.length % 2) + 1; i < ccnum.length; i += 2) {
        var digit = parseInt(ccnum.charAt(i - 1)) * 2;
        if (digit < 10) { checksum += digit; } else { checksum += (digit - 9); }
    }
    if ((checksum % 10) == 0) return true;
    else return false;
}