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

我搜索了很多信用卡格式和电话号码格式。找到了很多好的提示，但没有一个真正符合我的需求，所以我创建了这段代码。你可以这样使用它:

var sf = smartForm.formatCC(myInputString);
var cardType = sf.cardType;

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;
}

信用卡的第一个数字可以用来大致了解供应商:

签证:49、44或47 Visa电子:42、45、48、49 万事达卡:51 美国运通:34 就餐者:30、36、38 JCB: 35

斯威夫特 5+

extension String {
    
    func isMatch(_ Regex: String) -> Bool {
        
        do {
            let regex = try NSRegularExpression(pattern: Regex)
            let results = regex.matches(in: self, range: NSRange(self.startIndex..., in: self))
            return results.map {
                String(self[Range($0.range, in: self)!])
            }.count > 0
        } catch {
            return false
        }
        
    }
    
    func getCreditCardType() -> String? {
        
        let VISA_Regex = "^4[0-9]{6,}$"
        let MasterCard_Regex = "^5[1-5][0-9]{5,}|222[1-9][0-9]{3,}|22[3-9][0-9]{4,}|2[3-6][0-9]{5,}|27[01][0-9]{4,}|2720[0-9]{3,}$"
        let AmericanExpress_Regex = "^3[47][0-9]{5,}$"
        let DinersClub_Regex = "^3(?:0[0-5]|[68][0-9])[0-9]{4,}$"
        let Discover_Regex = "^6(?:011|5[0-9]{2})[0-9]{3,}$"
        let JCB_Regex = "^(?:2131|1800|35[0-9]{3})[0-9]{3,}$"
        
        if self.isMatch(VISA_Regex) {
            return "VISA"
        } else if self.isMatch(MasterCard_Regex) {
            return "MasterCard"
        } else if self.isMatch(AmericanExpress_Regex) {
            return "AmericanExpress"
        } else if self.isMatch(DinersClub_Regex) {
            return "DinersClub"
        } else if self.isMatch(Discover_Regex) {
            return "Discover"
        } else if self.isMatch(JCB_Regex) {
            return "JCB"
        } else {
            return nil
        }
        
    }
    
}

使用。

"1234123412341234".getCreditCardType()

只需一点点的勺子喂养:

$("#CreditCardNumber").focusout(function () {


        var regVisa = /^4[0-9]{12}(?:[0-9]{3})?$/;
        var regMasterCard = /^5[1-5][0-9]{14}$/;
        var regAmex = /^3[47][0-9]{13}$/;
        var regDiscover = /^6(?:011|5[0-9]{2})[0-9]{12}$/;

        if (regVisa.test($(this).val())) {
            $("#CCImage").html("<img height='40px' src='@Url.Content("~/images/visa.png")'>");          

        }

        else if (regMasterCard.test($(this).val())) {
        $("#CCImage").html("<img height='40px' src='@Url.Content("~/images/mastercard.png")'>");

        }

        else if (regAmex.test($(this).val())) {

           $("#CCImage").html("<img height='40px' src='@Url.Content("~/images/amex.png")'>");

        }
         else if (regDiscover.test($(this).val())) {

           $("#CCImage").html("<img height='40px' src='@Url.Content("~/images/discover.png")'>");

        }
        else {
        $("#CCImage").html("NA");

        }

    });