银行卡校验

复制import re

# Luhn 算法校验 + 发卡行识别（BIN 库）

BIN_DB = {
    "4": "Visa",
    "51": "Mastercard",
    "52": "Mastercard",
    "53": "Mastercard",
    "54": "Mastercard",
    "55": "Mastercard",
    "62": "China UnionPay",
    "6011": "Discover",
}

def luhn_check(card_num: str) -> bool:
    """Luhn 算法校验卡号合法性"""
    digits = [int(d) for d in card_num if d.isdigit()]
    if len(digits) < 2:
        return False
    # 从右向左，偶数位（从 1 开始计数）翻倍，大于 9 则减 9
    checksum = 0
    for i, d in enumerate(reversed(digits)):
        if i % 2 == 1:
            d *= 2
            if d > 9:
                d -= 9
        checksum += d
    return checksum % 10 == 0

def identify_issuer(card_num: str) -> str:
    """根据 BIN 识别发卡行"""
    clean = re.sub(r"\D", "", card_num)
    for prefix, issuer in sorted(BIN_DB.items(), key=lambda x: -len(x[0])):
        if clean.startswith(prefix):
            return issuer
    return "Unknown"

# 示例
card = "6222021234567890"
print(f"卡号: {card}")
print(f"Luhn 校验: {'通过' if luhn_check(card) else '失败'}")
print(f"发卡行: {identify_issuer(card)}")

复制package main

import (
	"fmt"
	"regexp"
	"sort"
	"strconv"
)

var binDB = map[string]string{
	"4":     "Visa",
	"51":    "Mastercard",
	"52":    "Mastercard",
	"53":    "Mastercard",
	"54":    "Mastercard",
	"55":    "Mastercard",
	"62":    "China UnionPay",
	"6011":  "Discover",
}

func luhnCheck(cardNum string) bool {
	re := regexp.MustCompile(`\D`)
	digitsStr := re.ReplaceAllString(cardNum, "")
	if len(digitsStr) < 2 {
		return false
	}
	digits := make([]int, len(digitsStr))
	for i, ch := range digitsStr {
		digits[i], _ = strconv.Atoi(string(ch))
	}
	checksum := 0
	for i := len(digits) - 1; i >= 0; i-- {
		d := digits[len(digits)-1-i]
		if i%2 == 1 {
			d *= 2
			if d > 9 {
				d -= 9
			}
		}
		checksum += d
	}
	return checksum%10 == 0
}

func identifyIssuer(cardNum string) string {
	re := regexp.MustCompile(`\D`)
	clean := re.ReplaceAllString(cardNum, "")
	// 按前缀长度降序匹配（长前缀优先）
	prefixes := make([]string, 0, len(binDB))
	for k := range binDB {
		prefixes = append(prefixes, k)
	}
	sort.Slice(prefixes, func(i, j int) bool {
		return len(prefixes[i]) > len(prefixes[j])
	})
	for _, prefix := range prefixes {
		if len(clean) >= len(prefix) && clean[:len(prefix)] == prefix {
			return binDB[prefix]
		}
	}
	return "Unknown"
}

func main() {
	card := "6222021234567890"
	fmt.Printf("卡号: %s\n", card)
	fmt.Printf("Luhn 校验: %t\n", luhnCheck(card))
	fmt.Printf("发卡行: %s\n", identifyIssuer(card))
}

复制// Luhn 算法 + BIN 识别（浏览器/Node.js 均可运行）

const BIN_DB = {
  '4': 'Visa',
  '51': 'Mastercard',
  '52': 'Mastercard',
  '53': 'Mastercard',
  '54': 'Mastercard',
  '55': 'Mastercard',
  '62': 'China UnionPay',
  '6011': 'Discover',
};

function luhnCheck(cardNum) {
  const digits = cardNum.replace(/\D/g, '').split('').map(Number);
  if (digits.length < 2) return false;
  let checksum = 0;
  for (let i = digits.length - 1; i >= 0; i--) {
    let d = digits[i];
    // 从右数第奇数位（1-based）翻倍
    if ((digits.length - 1 - i) % 2 === 1) {
      d *= 2;
      if (d > 9) d -= 9;
    }
    checksum += d;
  }
  return checksum % 10 === 0;
}

function identifyIssuer(cardNum) {
  const clean = cardNum.replace(/\D/g, '');
  // 按前缀长度降序匹配
  const sortedPrefixes = Object.keys(BIN_DB).sort((a, b) => b.length - a.length);
  for (const prefix of sortedPrefixes) {
    if (clean.startsWith(prefix)) {
      return BIN_DB[prefix];
    }
  }
  return 'Unknown';
}

// 示例
const card = '6222021234567890';
console.log(`卡号: ${card}`);
console.log(`Luhn 校验: ${luhnCheck(card) ? '通过' : '失败'}`);
console.log(`发卡行: ${identifyIssuer(card)}`);