from cs50 import get_int, get_string#Asking User For Credit Card Numberdef main(): while True: Credit_Card = str(get_int("Enter Credit Card Number: ")) if Credit_Card != "": break cardCheck(cardSum, Credit_Card)def cardSum(Credit_Card): even = 0 odd = 0 CC = len(Credit_Card) if (CC == 0): return 0 else: if (CC % 2 == 0): last = int(Credit_Card[-1]) even += last return even + cardSum(Credit_Card[:-1]) else: last = int(Credit_Card[-1]) last = last * 2 oddDigits = last // 10 + last % 10 odd += oddDigits return odd + cardSum(Credit_Card[:-1])#Checking is card valid or notdef cardCheck(cardSum,Credit_Card): Total = cardSum(Credit_Card) if (Total % 10 == 0): if (len(Credit_Card) == 15) and (int(Credit_Card[0:2]) in [37, 34]): print("AMEX") elif (len(Credit_Card) == 16) and (int(Credit_Card[:2]) in range(50, 56)): print("MASTER CARD") elif (len(Credit_Card) in [13, 16]) and (int(Credit_Card[:1]) == 4): print("VISA") else: print("INVALID") else: print("INVALID")if __name__ == "__main__": main()我無(wú)法弄清楚為什么我的程序沒(méi)有使用這些AMEX 卡號(hào)提供正確的輸出：378282246310005，371449635398431在我的 C 實(shí)現(xiàn)的積分中，這兩張卡顯示 AMEX 但在 python 中它顯示 INVALID 作為輸出它工作正常對(duì)于 Master，Visa
1 回答
HUX布斯
TA貢獻(xiàn)1876條經(jīng)驗(yàn) 獲得超6個(gè)贊
我認(rèn)為問(wèn)題在于您的代碼使用的是絕對(duì)奇偶校驗(yàn)而不是相對(duì)奇偶校驗(yàn)。也就是說(shuō)，我們從右邊的倒數(shù)第二個(gè)數(shù)字開始加倍，然后每隔一個(gè)數(shù)字向左移動(dòng)。但是要加倍的數(shù)字的指標(biāo)的奇偶性取決于原始數(shù)字的位數(shù)是奇數(shù)還是偶數(shù)。您的代碼沒(méi)有考慮到這一點(diǎn)。
我們需要在開始時(shí)計(jì)算卡片的奇偶校驗(yàn)，并通過(guò)遞歸cardSum()調(diào)用傳遞這個(gè)奇偶校驗(yàn)，所以它會(huì)加倍正確的數(shù)字：
def cardSum(digits, parity):
if not digits:
return 0
digit, digits = int(digits[-1]), digits[:-1]
if len(digits) % 2 == parity:
digit *= 2
digit = digit // 10 + digit % 10
return digit + cardSum(digits, parity)
def cardCheck(cardSum, credit_card):
checksum = cardSum(credit_card, len(credit_card) % 2)
if checksum % 10 == 0:
if len(credit_card) == 15 and int(credit_card[0:2]) in [34, 37]:
print("AMEX")
elif len(credit_card) == 16 and int(credit_card[:2]) in range(50, 56):
print("MASTER CARD")
elif len(credit_card) in [13, 16] and int(credit_card[:1]) == 4:
print("VISA")
else:
print("INVALID")
else:
print("INVALID")
if __name__ == "__main__":
credit_card = input("Enter Credit Card Number: ")
if credit_card != "":
cardCheck(cardSum, credit_card)
我猜這是 AMEX 提出來(lái)的，因?yàn)樗且粋€(gè)奇數(shù)長(zhǎng)度的數(shù)字——您是否測(cè)試過(guò)任何其他發(fā)卡機(jī)構(gòu)的奇數(shù)長(zhǎng)度數(shù)字？
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