1 00:00:00,000 --> 00:00:13,290 2 00:00:13,290 --> 00:00:14,570 >> Rob BOWDEN: Hi, mimi nina Rob. 3 00:00:14,570 --> 00:00:17,610 Na natumaini wewe ni kushtakiwa kwa ajili ya mikopo. 4 00:00:17,610 --> 00:00:20,710 Kitu hivyo kwanza tunahitaji kufanya ni kuomba kadi 5 00:00:20,710 --> 00:00:22,710 idadi kutoka kwa mtumiaji. 6 00:00:22,710 --> 00:00:25,060 Hapa, sisi ni kutumia getLongLong. 7 00:00:25,060 --> 00:00:29,070 Unaweza pia kutumika GetString, lakini katika kesi hiyo, d haja ya kuangalia 8 00:00:29,070 --> 00:00:32,340 kuwa kulikuwa hakuna mashirika yasiyo ya numeric wahusika katika kamba. 9 00:00:32,340 --> 00:00:34,560 Hivyo tutaweza kutumia getLongLong. 10 00:00:34,560 --> 00:00:38,070 >> Kumbuka kwamba huwezi kutumia kitu kama GetInt, tangu idadi itakuwa 11 00:00:38,070 --> 00:00:40,650 kubwa mno na kifafa katika integer. 12 00:00:40,650 --> 00:00:44,480 Mara baada ya sisi kuwa na idadi hiyo, sisi kuona hapa kitanzi hii wakati. 13 00:00:44,480 --> 00:00:48,210 Hivyo hii kitanzi wakati inatekeleza Algorithm Luhn ya kwamba 14 00:00:48,210 --> 00:00:50,980 kuona katika pset spec. 15 00:00:50,980 --> 00:00:53,830 >> Na ni kweli kwenda kuwa kidogo wajanja. 16 00:00:53,830 --> 00:01:00,800 Hivyo katika pset spec, taarifa kwamba Hatua moja na wawili tofauti. 17 00:01:00,800 --> 00:01:05,160 Sisi kwanza kwenda juu kadi nzima mikopo posta, kuangalia kwa kila mengine 18 00:01:05,160 --> 00:01:09,775 tabia ya kuanzia pili kwa tabia ya mwisho, na kuzidisha yao 19 00:01:09,775 --> 00:01:11,750 na kuongeza tarakimu wote. 20 00:01:11,750 --> 00:01:16,150 Kisha baada ya kuwa, sisi kuongeza katika yote ya tarakimu nyingine. 21 00:01:16,150 --> 00:01:20,660 >> Hivyo badala ya kufanya wale viwili hatua tofauti, tunakwenda kuchanganya 22 00:01:20,660 --> 00:01:24,430 yao katika moja iteration juu ya nzima kadi namba. 23 00:01:24,430 --> 00:01:29,710 Hapa, tunaona int cur tarakimu usawa kadi namba, mod 10. 24 00:01:29,710 --> 00:01:32,050 Kadi namba ni nini mod 10 kufanya? 25 00:01:32,050 --> 00:01:35,750 Ni anatupa tarakimu ya mwisho idadi nzima. 26 00:01:35,750 --> 00:01:39,340 Basi kumbuka kwamba kama sisi kugawanywa idadi up na 10, basi salio 27 00:01:39,340 --> 00:01:42,180 itakuwa chochote kile tarakimu ya mwisho ni. 28 00:01:42,180 --> 00:01:46,560 23 kugawanywa na 10, salio kuwa 3. 29 00:01:46,560 --> 00:01:53,760 >> Hivyo tarakimu ya mwisho, sasa hapa, tunaona sisi ni matawi juu ya mult kwa 2. 30 00:01:53,760 --> 00:01:57,630 Basi nini tunakwenda kutumia mult na 2 kwa ni kutofautisha kati ya 31 00:01:57,630 --> 00:02:02,110 moja ya "kila idadi nyingine kutoka pili tarakimu "idadi. 32 00:02:02,110 --> 00:02:08,310 Mult na 2 ni kwenda kuanza nje kama uongo, tangu tarakimu ya mwisho hawapaswi 33 00:02:08,310 --> 00:02:11,750 kuchukuliwa kutoka pili kwa mwisho tarakimu. 34 00:02:11,750 --> 00:02:16,760 >> Hivyo basi mwishoni mwa hii kwa kitanzi, sisi kuona kwamba tunakwenda kubadili hali hii 35 00:02:16,760 --> 00:02:18,870 kutoka kwenye uongo kwa kweli. 36 00:02:18,870 --> 00:02:22,520 On iteration ya pili ya kwa kitanzi, itakuja kuchukuliwa kweli mpaka 37 00:02:22,520 --> 00:02:25,090 mwisho, wakati sisi mabadiliko kutoka kweli na uongo. 38 00:02:25,090 --> 00:02:28,290 Kwa sababu basi tutaweza kuwa juu ya theluthi moja kwa tarakimu ya mwisho, ambayo si moja ya 39 00:02:28,290 --> 00:02:32,210 tarakimu kwamba tunapaswa kuzidisha kwa 2. 40 00:02:32,210 --> 00:02:37,410 >> Hivyo kama sisi kutokea kwa kuwa juu ya mmoja wa wale tarakimu kwamba tunataka kuzidisha kwa 2, 41 00:02:37,410 --> 00:02:40,610 tunaona sisi ni kuongeza kwa checksum yetu. 42 00:02:40,610 --> 00:02:43,640 Na hapa, sisi ni kutumia ternary operator kwa mara moja 43 00:02:43,640 --> 00:02:45,470 tena kuwa kidogo wajanja. 44 00:02:45,470 --> 00:02:50,170 Hivyo kama cur tarakimu ni chini ya 5, kisha tunaweza tu kufanya cur tarakimu mara 2. 45 00:02:50,170 --> 00:02:50,690 Hiyo ni rahisi. 46 00:02:50,690 --> 00:02:52,770 Kama ni 1, basi tunataka kuongeza 2. 47 00:02:52,770 --> 00:02:54,090 Kama ni 2, tunataka kuongeza 4. 48 00:02:54,090 --> 00:02:55,530 Kama ni 4, tunataka kuongeza 8. 49 00:02:55,530 --> 00:02:57,400 >> Basi nini maalum kuhusu 5? 50 00:02:57,400 --> 00:03:00,290 Naam, mara 5 2 ni 10. 51 00:03:00,290 --> 00:03:05,920 Na kukumbuka kutoka pset spec kwamba tunataka kuongeza tarakimu ya 52 00:03:05,920 --> 00:03:09,300 mara namba 2, na si mara namba 2 yenyewe. 53 00:03:09,300 --> 00:03:13,920 Hivyo kama idadi ya awali ni 7, 7 mara 2 ni 14. 54 00:03:13,920 --> 00:03:18,930 Tunataka kuongeza 1 pamoja na 4 idadi, si 14. 55 00:03:18,930 --> 00:03:24,050 >> Hivyo hapa, kama idadi ni 5 au zaidi, nini sisi ni kufanya ni cur tarakimu 56 00:03:24,050 --> 00:03:26,470 mara 2 minus 9. 57 00:03:26,470 --> 00:03:29,940 Na kama unafikiri juu ya kwamba, Mara 5 2 ni 10. 58 00:03:29,940 --> 00:03:33,130 Na hivyo sisi ni kuongeza 1, ambayo ni 10 minus 9. 59 00:03:33,130 --> 00:03:35,490 Na mara 6 2 ni 12. 60 00:03:35,490 --> 00:03:38,380 Hivyo sisi ni kuongeza 3, ambayo ni 12 minus 9. 61 00:03:38,380 --> 00:03:40,250 Na kwamba kazi kwa namba zote. 62 00:03:40,250 --> 00:03:43,330 >> Hivyo kwamba ni nini sisi ni kuongeza kwa checksum yetu. 63 00:03:43,330 --> 00:03:49,970 Na mwingine hii ni nini utunzaji Hatua ya Mbili za Luhn ya algorithm, ambayo ni haki 64 00:03:49,970 --> 00:03:55,010 kuongeza tarakimu kama haina kutokea kuwa moja ya kila tarakimu nyingine. 65 00:03:55,010 --> 00:04:01,440 Hivyo mara tuna kwamba, hii ni kuweka wimbo wa kwanza wahusika wawili ya 66 00:04:01,440 --> 00:04:05,220 kadi namba, mbili za kwanza tarakimu, tangu sisi ni hatimaye kwenda 67 00:04:05,220 --> 00:04:08,980 kutaka kutumia chini hapa kuthibitisha, yote ya haki, Visa ina kuanza 68 00:04:08,980 --> 00:04:14,440 na hii, na mahitaji ya American Express kuanza na hii, na kadhalika. 69 00:04:14,440 --> 00:04:16,850 >> Hatimaye, sisi kufanya kadi idadi sawa na kadi 70 00:04:16,850 --> 00:04:18,730 Idadi ya kugawanywa na 10. 71 00:04:18,730 --> 00:04:19,829 Kwa nini sisi kufanya hivyo? 72 00:04:19,829 --> 00:04:22,070 Naam, sisi tu kubebwa tarakimu ya mwisho. 73 00:04:22,070 --> 00:04:24,880 Kugawa na 10 kuhama idadi nzima juu. 74 00:04:24,880 --> 00:04:27,150 Hivyo sasa wakati sisi kitanzi nyuma, sisi ni kwenda kuwa utunzaji 75 00:04:27,150 --> 00:04:28,540 pili kwa mwisho tarakimu. 76 00:04:28,540 --> 00:04:31,060 Kisha wakati sisi hit hii tena, tunakwenda kukata pili kwa mara ya mwisho 77 00:04:31,060 --> 00:04:35,060 tarakimu, kitanzi nyuma, na kushughulikia tatu kwa mara ya mwisho tarakimu, na kadhalika, mpaka 78 00:04:35,060 --> 00:04:40,120 idadi fika 0, ambapo kiwango sisi kuvunja nje ya kitanzi wakati. 79 00:04:40,120 --> 00:04:43,560 >> Sisi ni pia kuweka wimbo wa mikopo kadi namba urefu, tangu kwamba 80 00:04:43,560 --> 00:04:48,440 muhimu kutofautisha iwapo ni kadi halali ya mkopo idadi. 81 00:04:48,440 --> 00:04:53,560 Basi sasa, mara moja tumekuwa mahesabu checksum, tunaweza kuamua kama 82 00:04:53,560 --> 00:04:55,180 ni kadi halali. 83 00:04:55,180 --> 00:04:58,010 checksum mod 10 ni sehemu ya algorithm Luhn ya. 84 00:04:58,010 --> 00:05:03,360 Kama checksum mod 10 anarudi kitu mashirika yasiyo ya sifuri, basi hii itakuwa kurudi kweli, 85 00:05:03,360 --> 00:05:06,650 katika kesi ambayo, idadi lazima batili. 86 00:05:06,650 --> 00:05:12,590 >> Vinginevyo, kama checksum mod 10 ni 0, basi tunaweza kuendelea. 87 00:05:12,590 --> 00:05:18,360 Hii kubwa mwingine kama ni kusema, kama kwanza tarakimu mbili ni sawa na AMEX 1, 88 00:05:18,360 --> 00:05:23,640 ambapo hadi hapa, tunaona kwamba AMEX 1, kama kwa spec, ni 34. 89 00:05:23,640 --> 00:05:26,595 Na tutaweza pia kulinganisha kwa AMEX 2, ambayo ni 37. 90 00:05:26,595 --> 00:05:30,360 91 00:05:30,360 --> 00:05:34,210 Na kadi namba urefu ni sawa na American inatarajiwa Express 92 00:05:34,210 --> 00:05:37,910 kadi urefu, basi tunaweza magazeti American Express. 93 00:05:37,910 --> 00:05:41,920 >> Tutaweza kufanya kitu sawa na Visa. 94 00:05:41,920 --> 00:05:51,940 tarakimu mbili za kwanza haja ya kuwa na zaidi kuliko au sawa na 40, au chini ya 95 00:05:51,940 --> 00:05:54,290 kuliko au sawa na 49. 96 00:05:54,290 --> 00:05:57,180 Wale kuwakilisha kadi halali Visa. 97 00:05:57,180 --> 00:06:01,530 Na urefu mahitaji ya kuwa sawa na Visa Length 1 au Visa Length 2. 98 00:06:01,530 --> 00:06:07,320 Na hivyo urefu lazima aidha 13 au 16 tarakimu kwa muda mrefu. 99 00:06:07,320 --> 00:06:12,240 >> Na hatimaye kwa MasterCard, ni sawa na Visa, kwamba mbili za kwanza 100 00:06:12,240 --> 00:06:15,340 tarakimu haja ya kuwa katika baadhi ya mbalimbali, na urefu lazima 101 00:06:15,340 --> 00:06:19,440 kuwa na hasa 16 tarakimu. 102 00:06:19,440 --> 00:06:24,390 Hivyo kama yoyote ya kesi hizo kushikilia, kisha katika kesi ya kwanza, tutaweza magazeti AMEX. 103 00:06:24,390 --> 00:06:26,310 Kama kesi hii ana, tutaweza magazeti Visa. 104 00:06:26,310 --> 00:06:28,400 Kama kesi hii ana, tutaweza magazeti MasterCard. 105 00:06:28,400 --> 00:06:32,170 >> Lakini kama hakuna wale kushikilia, hata kama checksum ilikuwa halali, 106 00:06:32,170 --> 00:06:33,900 sisi bado magazeti batili. 107 00:06:33,900 --> 00:06:37,050 Kwa sababu si moja ya wale aina ya kadi. 108 00:06:37,050 --> 00:06:40,030 Jina langu ni Rob, na natumaini kupatikana mikopo ya kuvutia. 109 00:06:40,030 --> 00:06:46,272