1 00:00:00,000 --> 00:00:05,960 >> [Daqq tal-mużika] 2 00:00:05,960 --> 00:00:08,540 >> Doug LLOYD: Hi, so ejja jitkellmu dwar operaturi C. 3 00:00:08,540 --> 00:00:12,590 Allura, konna diġà tidher waħda, fil-fatt, huwa daqs il-operatur assenjazzjoni. 4 00:00:12,590 --> 00:00:15,510 Dan jippermetti li biss jitqiegħed valur fis varjabbli. 5 00:00:15,510 --> 00:00:18,046 Dik hija l-assenjazzjoni operatur, sinjal ugwali wieħed. 6 00:00:18,046 --> 00:00:20,670 Sabiex jimmanipulaw u xogħol mal-valuri u varjabbli fis-C, 7 00:00:20,670 --> 00:00:23,710 għandna numru ta 'operaturi għad-dispożizzjoni tagħna li nistgħu nużaw. 8 00:00:23,710 --> 00:00:25,543 Ejja tagħti ħarsa lejn xi wħud mill-dawk komuni 9 00:00:25,543 --> 00:00:27,430 tibda bil operaturi aritmetika. 10 00:00:27,430 --> 00:00:31,080 Kif inti tista 'tistenna, nistgħu nagħmlu operazzjonijiet pretty matematika bażiċi fil C. 11 00:00:31,080 --> 00:00:36,520 Aħna tista 'żżid, naqqas, immoltiplika, u numri firda li jużaw plus, minus, star, 12 00:00:36,520 --> 00:00:38,422 u slash, rispettivament. 13 00:00:38,422 --> 00:00:40,630 Hawn koppja ta 'linji ta' kodiċi li aħna tagħmel dan. 14 00:00:40,630 --> 00:00:44,150 Allura, aħna għandna int x ugwali y flimkien ma '1. 15 00:00:44,150 --> 00:00:46,460 Ejja nassumu li x'imkien up fuq din il-linja tal-kodiċi 16 00:00:46,460 --> 00:00:49,230 kellna qal y int ugwali għal 10. 17 00:00:49,230 --> 00:00:55,790 X'inhu l-valur ta 'x wara I tesegwixxi dan l-ewwel linja tal-kodiċi? 18 00:00:55,790 --> 00:00:56,700 Did you say 11? 19 00:00:56,700 --> 00:00:57,910 Youd dritt. 20 00:00:57,910 --> 00:00:58,420 Għaliex huwa li? 21 00:00:58,420 --> 00:00:59,790 Well, y kien 10. 22 00:00:59,790 --> 00:01:03,215 Xi int Jien qal x ugwali għal 10 flimkien ma '1. 23 00:01:03,215 --> 00:01:04,269 10 plus 1 huwa 11. 24 00:01:04,269 --> 00:01:08,540 Allura, il-valur 11 gets maħżuna fil-varjabbli x. 25 00:01:08,540 --> 00:01:09,740 Mhux wisq ħażina, right? 26 00:01:09,740 --> 00:01:14,040 >> Kif dwar din il-linja li jmiss ta ' kodiċi? x ugwali x żminijiet 5. 27 00:01:14,040 --> 00:01:17,700 Ukoll, qabel we esegwiti din il-linja ta 'kodiċi, x kien 11. 28 00:01:17,700 --> 00:01:21,237 Allura, x'inhu l-valur ta ' x wara din il-linja tal-kodiċi? 29 00:01:21,237 --> 00:01:21,820 Tieħu t-tieni. 30 00:01:21,820 --> 00:01:24,710 31 00:01:24,710 --> 00:01:27,620 Allura, x ugwali x żminijiet 5. 32 00:01:27,620 --> 00:01:29,850 x kien 11. 33 00:01:29,850 --> 00:01:32,970 Allura, x ugwali 11-il darba 5. 34 00:01:32,970 --> 00:01:34,360 Jew 55. 35 00:01:34,360 --> 00:01:36,490 Mela jekk inti qal 55, youd tkun id-dritt. 36 00:01:36,490 --> 00:01:41,770 >> Issa, jista 'jkun ftit konfuża, iżda bil-mod li assenjazzjoni jaħdem C 37 00:01:41,770 --> 00:01:46,030 huwa l-valur fuq il-lemin gets assenjat lill-valur fuq ix-xellug. 38 00:01:46,030 --> 00:01:49,090 Allura, l-ewwel aħna tevalwa x żminijiet 5. 39 00:01:49,090 --> 00:01:50,800 Allura, 11-il darba 5 huwa 55. 40 00:01:50,800 --> 00:01:53,340 U allura aħna maħżen li valur x. 41 00:01:53,340 --> 00:01:56,100 Il-11 li kien hemm qabel issa qed jinkiteb fuqhom. 42 00:01:56,100 --> 00:01:58,280 Allura valur x taċ issa 55 hu. 43 00:01:58,280 --> 00:02:00,820 Nisperaw li pjuttost sempliċi. 44 00:02:00,820 --> 00:02:04,246 >> Hemm operatur ieħor li inti stajt probabbilment mhux neċessarjament jinstemgħu 45 00:02:04,246 --> 00:02:06,620 sejjaħ dan, imma inti stajt ċertament ħadem fil-passat 46 00:02:06,620 --> 00:02:09,470 jekk inti tiftakar ġurnata tiegħek ta 'żmien twil diviżjoni mod lura fl-iskola grad. 47 00:02:09,470 --> 00:02:11,270 Huwa sejjaħ l-operatur modulus. 48 00:02:11,270 --> 00:02:13,620 X'inhu modulus ma huwa jagħtik l-bqija 49 00:02:13,620 --> 00:02:15,400 meta inti jaqsmu żewġ numri flimkien. 50 00:02:15,400 --> 00:02:21,750 Għalhekk, jekk ngħid 13 diviż bl 4, x'inhu l-bqija? 51 00:02:21,750 --> 00:02:24,860 U li l-valur ikun ikkalkolat mill-operatur modulus. 52 00:02:24,860 --> 00:02:28,320 >> So, I jkollhom linja tal-kodiċi hawn, int m ugwali 13 mod 4. 53 00:02:28,320 --> 00:02:31,960 U jien ngħid hawn fil kumment valur li m issa huwa 1. 54 00:02:31,960 --> 00:02:32,750 Għaliex għandi ngħid li? 55 00:02:32,750 --> 00:02:36,270 Ukoll, jagħmlu l-diviżjoni twila fil tiegħek ras, jekk inti jkollhom miegħi għat-tieni. 56 00:02:36,270 --> 00:02:40,070 So, I 4 diviża bi 13. 57 00:02:40,070 --> 00:02:44,087 4 tmur fi 13 tliet darbiet bil-bqija tal-1. 58 00:02:44,087 --> 00:02:45,920 Allura, bażikament, l- operatur modulus ma 59 00:02:45,920 --> 00:02:48,600 huwa jgħidlek meta inti qasma, ikollok l-bqija. 60 00:02:48,600 --> 00:02:51,420 Għandek mnejn taħseb li attwalment mhux xi ħaġa terriblement utli, 61 00:02:51,420 --> 00:02:54,350 imma youd tkun sorpriż, fil-fatt, billi kemm spiss li modulus 62 00:02:54,350 --> 00:02:55,820 operatur jista 'jidħol fil handy. 63 00:02:55,820 --> 00:02:58,420 >> Hemm ftit ta 'problemi aħna ser nagħmlu CS50 li jittrattaw dan. 64 00:02:58,420 --> 00:03:00,545 Huwa wkoll tajjeb biex isir affarijiet simili numru bl-addoċċ. 65 00:03:00,545 --> 00:03:03,850 Għalhekk, per eżempju jekk inti stajt qatt sema ta 'ġeneratur numru bl-addoċċ, 66 00:03:03,850 --> 00:03:06,620 li għaddej biex jagħtuk numru minn 0 sa xi numru kbir. 67 00:03:06,620 --> 00:03:10,390 Imma forsi inti biss verament bżonn ta 'numru 0-20. 68 00:03:10,390 --> 00:03:13,425 Jekk inti tuża l-operatur modulus fuq dak in-numru ġgant li 69 00:03:13,425 --> 00:03:17,080 gets iġġenerat mill- ġeneratur numru bl-addoċċ, 70 00:03:17,080 --> 00:03:20,230 int ser jieħdu kwalunkwe valur enormi huwa, jaqsamha b'20, 71 00:03:20,230 --> 00:03:21,210 u jiksbu l-bqija. 72 00:03:21,210 --> 00:03:24,050 Il-bqija jista 'biss tkun valur 0-19. 73 00:03:24,050 --> 00:03:27,140 Allura, tuża operatur modulus biex jieħdu dan in-numru kbir 74 00:03:27,140 --> 00:03:29,640 u Whittle l-isfel fis xi ħaġa ftit aktar sinifikanti. 75 00:03:29,640 --> 00:03:31,764 Jien pretty żgur li int ser tkun jistgħu jużaw kemm ta 'dawk 76 00:03:31,764 --> 00:03:34,710 f'xi punt fil-futur CS50. 77 00:03:34,710 --> 00:03:37,030 >> Allura, C tagħtina wkoll mod li japplika aritmetika 78 00:03:37,030 --> 00:03:39,910 operatur għal varjabbli waħda fi ftit b'mod aktar shorthand. 79 00:03:39,910 --> 00:03:44,520 Allura, fil-slide ta 'qabel, rajna x ugwali x żminijiet 5. 80 00:03:44,520 --> 00:03:45,260 Li ħadmu. 81 00:03:45,260 --> 00:03:47,660 x drabi 5 allura gets maħżuna lura fil x. 82 00:03:47,660 --> 00:03:52,490 Hemm mod iqsar biex tagħmel dan, ħsieb, u huwa l-ħinijiet sintassi x ugwali 5. 83 00:03:52,490 --> 00:03:55,020 Huwa l-istess ħaġa eżatt kif qal x ugwali x żminijiet 5. 84 00:03:55,020 --> 00:03:56,824 Huwa biss ftit mod iqsar biex tagħmel dan. 85 00:03:56,824 --> 00:03:58,740 U meta tara xi kodiċi distribuzzjoni jew inti 86 00:03:58,740 --> 00:04:01,287 tara xi kodiċi kampjun li ma affarijiet bħal dan, 87 00:04:01,287 --> 00:04:03,120 biss ikunu familjari mal dak l-sintassi mezzi. 88 00:04:03,120 --> 00:04:05,980 Inti żgur ma għandekx jużawh, imma jekk inti tagħmel, 89 00:04:05,980 --> 00:04:08,235 jista 'jagħmel kodiċi tiegħek tfittex slicker ftit. 90 00:04:08,235 --> 00:04:11,360 U taf li inti tista 'wkoll tuża kwalunkwe l-operaturi differenti konna diġà 91 00:04:11,360 --> 00:04:12,660 rajna qabel minflok ta 'drabi. 92 00:04:12,660 --> 00:04:16,720 Tista 'tgħid x plus ugwali 5, nieqes ugwali 5, il-ħinijiet, firda, u mod. 93 00:04:16,720 --> 00:04:18,959 Dawk kollha tax-xogħol. 94 00:04:18,959 --> 00:04:21,089 >> Hemm ukoll xi ħaġa dan huwa tant komuni fil C 95 00:04:21,089 --> 00:04:24,080 li aħna iddeċidejt li jirfinaw li anke aktar. 96 00:04:24,080 --> 00:04:26,916 Inkrementazzjoni varjabbli minn 1 jew decrementing varjabbli minn 1 97 00:04:26,916 --> 00:04:30,040 huwa tali thing-- komuni speċjalment meta nitkellmu dwar linji ftit aktar tard 98 00:04:30,040 --> 00:04:35,240 on-- li aħna iddeċidejt minflok tgħid xi ħaġa bħal x plus ugwali 1, 99 00:04:35,240 --> 00:04:40,190 jew x ugwali x flimkien ma '1, konna anke qasir mogħtija li biex x plus plus. 100 00:04:40,190 --> 00:04:46,940 Allura, x ugwali x plus 1, x plus ugwali 1, u x plus plus kollha jagħmlu l-istess ħaġa. 101 00:04:46,940 --> 00:04:48,470 Huma kollha inkrement x b'1. 102 00:04:48,470 --> 00:04:50,630 Iżda dan inkrementazzjoni u decrementing b'1 103 00:04:50,630 --> 00:04:54,110 hija tant komuni li għandna plus plus u minus minus 104 00:04:54,110 --> 00:04:59,140 li jippermettu magħna biex shorthand li anke aktar. 105 00:04:59,140 --> 00:05:02,110 >> Allura, ejja gerijiet swiċċ għat-tieni u jitkellmu dwar espressjonijiet Boolean. 106 00:05:02,110 --> 00:05:06,340 Kollha li huma wkoll tip ta 'jaqgħu il-kategorija ġenerali tal-operaturi. 107 00:05:06,340 --> 00:05:09,030 Iżda espressjonijiet Boolean, b'differenza operaturi aritmetika, 108 00:05:09,030 --> 00:05:11,860 huma użati għat-tqabbil valuri. 109 00:05:11,860 --> 00:05:15,550 Allura, għal darb'oħra, espressjonijiet Boolean kollha fl C tevalwa lil wieħed minn żewġ valuri possibbli, 110 00:05:15,550 --> 00:05:16,050 recall. 111 00:05:16,050 --> 00:05:17,740 Veru jew falz. 112 00:05:17,740 --> 00:05:21,880 Dik hija l-uniċi żewġ valuri li Varjabbli Boolean tista 'tieħu dwar. 113 00:05:21,880 --> 00:05:25,780 Nistgħu jużaw ir-riżultati ta 'espressjoni Boolean 114 00:05:25,780 --> 00:05:27,650 fil-lott ta 'modi fl-ipprogrammar. 115 00:05:27,650 --> 00:05:29,400 Fil-fatt, inti ser tkun tagħmel dan pjuttost ħafna. 116 00:05:29,400 --> 00:05:32,870 >> Per eżempju, aħna tista 'tiddeċiedi, ukoll, jekk xi kondizzjoni hija vera, 117 00:05:32,870 --> 00:05:34,665 forsi I ser tieħu din fergħa isfel kodiċi tiegħi. 118 00:05:34,665 --> 00:05:35,980 A kundizzjonali, biex ngħidu hekk. 119 00:05:35,980 --> 00:05:37,970 Aħna ser jitgħallmu dwar dawk dalwaqt wisq. 120 00:05:37,970 --> 00:05:40,560 Jew forsi, sakemm dan huwa minnu, nixtieq 121 00:05:40,560 --> 00:05:42,790 biex tkompli tagħmel dan aktar u aktar u aktar. 122 00:05:42,790 --> 00:05:43,480 A loop. 123 00:05:43,480 --> 00:05:48,350 Fiż-żewġ każijiet, jafu li aħna qed tuża espressjoni Boolean, vera jew falza, 124 00:05:48,350 --> 00:05:52,411 li jiddeċiedu jekk jew le li tieħu triq partikolari. 125 00:05:52,411 --> 00:05:54,660 Xi kultant meta aħna qed jaħdmu ma espressjonijiet Boolean, 126 00:05:54,660 --> 00:05:56,410 se nużaw varjabbli tat-tip BOOL. 127 00:05:56,410 --> 00:05:58,461 Inti jista 'jkollok ddikjaraw a BOOL ittajpjat varjabbli, 128 00:05:58,461 --> 00:06:00,210 u inti ser tuża fil tiegħek Espressjoni Boolean. 129 00:06:00,210 --> 00:06:02,130 Imma inti ma dejjem għandek tagħmel. 130 00:06:02,130 --> 00:06:06,690 Kif jirriżulta, fis-C, kull nuqqas ta '0 valur huwa l-istess kif qal veru. 131 00:06:06,690 --> 00:06:10,680 Jekk inti kienu ddikjaraw a varjabbli ta 'tip Boolean, 132 00:06:10,680 --> 00:06:14,240 u assenjati lilha l-valur veru, li l-istess bħal tiddikjara integer 133 00:06:14,240 --> 00:06:17,410 u assenjazzjoni tiegħu l-valur 1, 2, 3, jew verament xi valur 134 00:06:17,410 --> 00:06:19,580 tkun xi tkun differenti minn 0. 135 00:06:19,580 --> 00:06:22,690 Minħabba fis-C, kull-0 non valur huwa veru. 136 00:06:22,690 --> 00:06:24,820 0, min-naħa l-oħra, hija falza. 137 00:06:24,820 --> 00:06:27,162 Dan jista 'jidħol fil handy aktar tard li jkunu jafu, 138 00:06:27,162 --> 00:06:28,620 iżda biss xi ħaġa li wieħed iżomm f'moħħu. 139 00:06:28,620 --> 00:06:31,890 Aħna mhux dejjem ikollhom biex jużaw Varjabbli tip Boolean meta aħna 140 00:06:31,890 --> 00:06:34,980 qed jaħdmu ma 'espressjonijiet Boolean. 141 00:06:34,980 --> 00:06:37,890 >> Hemm żewġ tipi ewlenin ta 'Boolean espressjonijiet li aħna ser jaħdmu magħhom. 142 00:06:37,890 --> 00:06:40,640 Operaturi loġiċi u dawk operaturi relazzjonali. 143 00:06:40,640 --> 00:06:42,640 Il-lingwa hemm mhux terriblement importanti. 144 00:06:42,640 --> 00:06:44,970 Huwa tassew kemm jien jingħaqdu. 145 00:06:44,970 --> 00:06:49,222 U inti taf żgur, I think, malajr jirrealizzaw dak operatur relazzjonali hija, 146 00:06:49,222 --> 00:06:51,680 ibbażati fuq dak li huma meta aħna jitkellmu dwarhom fit-tieni. 147 00:06:51,680 --> 00:06:54,250 Imma ma joqogħdu jinkwetaw dwar neċessarjament memorizing l-operatur loġiku terminu 148 00:06:54,250 --> 00:06:55,460 jew operatur relazzjonali. 149 00:06:55,460 --> 00:07:00,070 Jien biss jużawha għall-grupp minnhom b'mod loġiku. 150 00:07:00,070 --> 00:07:02,620 >> Allura, ejja tagħti ħarsa lejn it-tliet operaturi loġiċi 151 00:07:02,620 --> 00:07:04,970 li aħna ser tara pjuttost bit fil-programmazzjoni fil CS50 152 00:07:04,970 --> 00:07:06,710 u fl-ipprogrammar aktar ġenerali. 153 00:07:06,710 --> 00:07:10,470 Logical U huwa veru, jekk u biss jekk iż-żewġ isiru operazzjonijiet matematiċi huma veri. 154 00:07:10,470 --> 00:07:11,775 Inkella falza. 155 00:07:11,775 --> 00:07:12,650 Fejn jfisser? 156 00:07:12,650 --> 00:07:15,840 Allura, ejja ngħidu li jien bi punt fil-kodiċi tiegħi fejn I jkollhom 157 00:07:15,840 --> 00:07:18,310 żewġ varjabbli, xuy. 158 00:07:18,310 --> 00:07:21,620 U nixtieq li jiddeċiedu jekk li jagħmel xi ħaġa fil-kodiċi tiegħi 159 00:07:21,620 --> 00:07:25,780 ibbażata fuq jekk x hija vera u y huwa veru. 160 00:07:25,780 --> 00:07:27,730 I biss tixtieq li tagħmel dan jekk tnejn minnhom huma veri, 161 00:07:27,730 --> 00:07:30,980 inkella Ma rridx li jinżlu li triq għaliex mhuwiex ser għinni. 162 00:07:30,980 --> 00:07:37,420 What nista 'ngħid huwa jekk x & & y. 163 00:07:37,420 --> 00:07:42,380 Li se jkun Boolean loġiku espressjoni jitqabblu x uy 164 00:07:42,380 --> 00:07:45,240 u tieħu triq ċerta ibbażati fuq dak l-valuri tagħhom huma. 165 00:07:45,240 --> 00:07:48,400 Għalhekk, jekk x hija vera u y huwa veru ibbażati fuq din it-tabella verità hawnhekk, 166 00:07:48,400 --> 00:07:50,430 biss allura aħna se jinżlu f'din it-triq. 167 00:07:50,430 --> 00:07:52,940 Jekk x, & & y. 168 00:07:52,940 --> 00:07:58,320 Huwa biss true-- l u biss minnu jekk x hija vera u y huwa veru. 169 00:07:58,320 --> 00:08:00,850 Jekk xi waħda hija falza, kif naraw l-tabella verità, 170 00:08:00,850 --> 00:08:02,370 imbagħad kemm xuy huma mhux veru. 171 00:08:02,370 --> 00:08:07,660 U għalhekk, x & & y hija falza. 172 00:08:07,660 --> 00:08:12,044 >> Logical OR huwa minnu jekk u biss jekk operand talanqas wieħed minnhom ikun veru. 173 00:08:12,044 --> 00:08:12,710 Inkella falza. 174 00:08:12,710 --> 00:08:15,760 Allura loġiku U meħtieġ kemm x uy biex ikunu vera. 175 00:08:15,760 --> 00:08:21,185 Logical JEW teħtieġ x biex ikunu vera jew y biex ikunu vera jew kemm xuy li jkun veru. 176 00:08:21,185 --> 00:08:23,310 Allura, għal darb'oħra, aħna tip ta 'ssib lilna nfusna f'sitwazzjoni 177 00:08:23,310 --> 00:08:26,460 fejn aħna qed tmur għall-kodiċi tagħna, u lħaqna furketta fit-triq. 178 00:08:26,460 --> 00:08:29,850 U rridu li jinżlu partikolari passaġġ jekk x huwa veru 179 00:08:29,850 --> 00:08:33,299 jew y huwa veru, iżda mhux bilfors jekk iż-żewġ huma veri. 180 00:08:33,299 --> 00:08:35,830 Imma possibilment jekk iż-żewġ huma veri. 181 00:08:35,830 --> 00:08:38,460 Mela jekk x hija vera u y hija vera, aħna ser jinżlu f'din it-triq. 182 00:08:38,460 --> 00:08:39,066 x hija veru. 183 00:08:39,066 --> 00:08:40,190 Waħda minnhom hija vera, right? 184 00:08:40,190 --> 00:08:42,080 Jekk x hija vera u y huwa veru. 185 00:08:42,080 --> 00:08:44,910 Jekk x hija vera, u y hija falza, wieħed minnhom għadu vera. 186 00:08:44,910 --> 00:08:48,020 Allura, x jew y għadu vera. 187 00:08:48,020 --> 00:08:52,290 Jekk x hija falza, u y huwa minnu, wieħed minnhom għadu vera, right? 188 00:08:52,290 --> 00:08:53,290 y hija vera, f'dan il-każ. 189 00:08:53,290 --> 00:08:57,950 Allura, huwa veru li x jew y huwa veru. 190 00:08:57,950 --> 00:09:02,620 Huwa biss jekk x hija falza u y hija falza do we ma jinżlu f'din it-triq, 191 00:09:02,620 --> 00:09:04,454 minħabba li la x lanqas y huwa veru. 192 00:09:04,454 --> 00:09:06,370 Issa, jekk inti qed tfittex lejn l-iskrin dritt issa 193 00:09:06,370 --> 00:09:09,062 u mintix dak li simbolu huwa għall loġiku JEW, 194 00:09:09,062 --> 00:09:10,270 huwa msejjaħ il-bar vertikali. 195 00:09:10,270 --> 00:09:13,730 U jekk inti tħares lejn tastiera tiegħek għal minuta, li qed nagħmel issa, 196 00:09:13,730 --> 00:09:16,940 huwa ġeneralment eżatt fuq il- Ikteb ewlenin, fuq l-aktar tastieri, 197 00:09:16,940 --> 00:09:19,630 fuq l-istess ċavetta bħall-backslash. 198 00:09:19,630 --> 00:09:22,790 Huwa wkoll ġeneralment id-dritt li jmiss għall-parentesi kwadri. 199 00:09:22,790 --> 00:09:27,240 Allura, jista 'jkun importanti li inti ma ittajpjat ħafna fil-passat. 200 00:09:27,240 --> 00:09:29,700 Iżda, jekk int qatt tagħmel paraguni loġiku, 201 00:09:29,700 --> 00:09:31,882 kif aħna ser tkun qiegħda tagħmel ħafna fil-kors, huwa 202 00:09:31,882 --> 00:09:33,840 se jkun utli li issib li ewlieni u jużawh. 203 00:09:33,840 --> 00:09:38,340 Għalhekk, huwa normalment fuq l-istess ċavetta kif backslash eżatt fuq Ikteb. 204 00:09:38,340 --> 00:09:39,757 >> L-operatur loġiku finali mhuwiex. 205 00:09:39,757 --> 00:09:41,131 U MHUX pjuttost sempliċi. 206 00:09:41,131 --> 00:09:42,830 Hija inverts-valur tal operand tagħha. 207 00:09:42,830 --> 00:09:46,080 Jekk x huwa minnu, allura ma x hija falza. 208 00:09:46,080 --> 00:09:49,960 Jekk x hija falza, allura ma x huwa veru. 209 00:09:49,960 --> 00:09:53,850 Kultant inti ser tisma dan is-simbolu ppronunzjata bħala bang jew exclamation 210 00:09:53,850 --> 00:09:55,231 jew le. 211 00:09:55,231 --> 00:09:56,730 Dan kollu l-istess ħaġa pjuttost ħafna. 212 00:09:56,730 --> 00:10:00,185 Fil-każ li inti tisma li mitkellma u int ma tkunx ċert dak li tfisser, 213 00:10:00,185 --> 00:10:02,310 huwa biss l-exclamation punt, iżda xi kultant huwa 214 00:10:02,310 --> 00:10:04,215 imsejħa ftit affarijiet differenti. 215 00:10:04,215 --> 00:10:06,340 Kull dritt, hekk li jieħu kura ta 'operaturi loġiċi. 216 00:10:06,340 --> 00:10:08,640 Allura, ejja nitkellmu dwar operaturi relazzjonali. 217 00:10:08,640 --> 00:10:11,610 Għal darb'oħra, jekk int familjari ma 'dan aritmetika lura fl-iskola grad, 218 00:10:11,610 --> 00:10:13,870 int probabilment familjari kif jaħdmu dawn diġà. 219 00:10:13,870 --> 00:10:15,411 Dawn jaġixxu eżattament kif youd jistennew. 220 00:10:15,411 --> 00:10:19,800 Allura inqas minn huwa veru, f'dan eżempju, jekk x huwa inqas minn y. 221 00:10:19,800 --> 00:10:24,380 Għalhekk, jekk x huwa ta '4 u y hija 6, x hija inqas minn y. 222 00:10:24,380 --> 00:10:26,035 Veru. 223 00:10:26,035 --> 00:10:27,910 Inqas minn jew ugwali għal xogħlijiet pretty simili. 224 00:10:27,910 --> 00:10:33,020 Jekk x huwa ta '4, u y hija 4, imbagħad x hija inqas minn jew ugwali għal y. 225 00:10:33,020 --> 00:10:35,310 Akbar minn. x hija akbar minn y. 226 00:10:35,310 --> 00:10:39,310 U ikbar minn jew ugwali għal, x hija akbar minn jew ugwali għal y. 227 00:10:39,310 --> 00:10:41,745 Jekk huwa veru, allura inti ser jgħaddu dik l-espressjoni, 228 00:10:41,745 --> 00:10:44,490 u tkun taf jinżlu dik it-triq fuq it-triq. 229 00:10:44,490 --> 00:10:48,590 Jekk għandek jekk x huwa akbar minn y, u x hija, fil-fatt, huwa akbar minn y, 230 00:10:48,590 --> 00:10:51,670 inti ser tagħmel dak kollu li huwa suġġett għall-kondizzjoni. 231 00:10:51,670 --> 00:10:54,396 >> Avviż li aħna ma jkollhomx karattru wieħed għal inqas minn 232 00:10:54,396 --> 00:10:57,020 jew ugwali għal, kif inti tista 'tkun familjari ma 'mill-kotba matematika. 233 00:10:57,020 --> 00:10:59,874 Allura, aħna għandna l-inqas minn simbolu, segwit minn sinjal ugwali. 234 00:10:59,874 --> 00:11:01,790 Li kif aħna nirrappreżentaw inqas minn jew ugwali għal. 235 00:11:01,790 --> 00:11:04,490 U l-istess, nistgħu nagħmlu dan għal aktar minn jew ugwali għal. 236 00:11:04,490 --> 00:11:06,698 >> L-aħħar żewġ relazzjonali operaturi li huma importanti 237 00:11:06,698 --> 00:11:09,320 huma l-ittestjar għall-ugwaljanza u l-inugwaljanza. 238 00:11:09,320 --> 00:11:13,380 Għalhekk, jekk x ugwali ugwali y, huwa veru jekk x uy tal-valur hija l-istess. 239 00:11:13,380 --> 00:11:19,610 Jekk x huwa 10, u y huwa 10, imbagħad x ugwali ugwali y huwa veru. 240 00:11:19,610 --> 00:11:26,010 Jekk x huwa 10 u y hija 11, x ugwali ugwali y mhux veru. 241 00:11:26,010 --> 00:11:29,680 Nistgħu wkoll test għall-inugwaljanza użu punt exclamation jew bang jew le, 242 00:11:29,680 --> 00:11:30,330 mill-ġdid. 243 00:11:30,330 --> 00:11:35,049 Jekk x mhuwiex ugwali għal y, jekk dan huwa t-test we qed tuża hawn, 244 00:11:35,049 --> 00:11:35,840 aħna'd tkun tajba biex tmur. 245 00:11:35,840 --> 00:11:40,340 Għalhekk, jekk x mhuwiex ugwali għal y, aħna ser jinżlu f'din it-triq. 246 00:11:40,340 --> 00:11:41,441 >> Jkun verament attenti hawn. 247 00:11:41,441 --> 00:11:44,440 Huwa mistake-- verament komuni u wieħed I ċertament issir pjuttost ħafna meta 248 00:11:44,440 --> 00:11:47,340 I kien qed started-- li aċċidentalment żball 249 00:11:47,340 --> 00:11:51,690 l-operatur assenjazzjoni, ugwali waħda, għall-operatur paragun ugwaljanza, 250 00:11:51,690 --> 00:11:52,582 ugwali doppja. 251 00:11:52,582 --> 00:11:54,540 Hija ser twassal għal xi stramb imġieba fil-kodiċi tiegħek, 252 00:11:54,540 --> 00:11:56,730 u normalment l-kompilatur se twissi inti dwar dan meta inti tipprova 253 00:11:56,730 --> 00:11:59,910 u jikkumpilaw kodiċi tiegħek, imma xi kultant inti tista 'tkun kapaċi li Sneak lilu mill. 254 00:11:59,910 --> 00:12:02,770 Mhuwiex neċessarjament ħaġa tajba li inti Sneak dan minn, għalkemm. 255 00:12:02,770 --> 00:12:04,710 Just hekk jekk inti qiegħed tagħmel test inugwaljanza, 256 00:12:04,710 --> 00:12:07,970 jekk int verifika jekk tnejn varjabbli differenti għandhom l-istess valur 257 00:12:07,970 --> 00:12:11,980 ġewwa minnhom, kun żgur li jużaw ugwali ugwali, u ugwali mhux wieħed. 258 00:12:11,980 --> 00:12:15,450 U li mod program tiegħek ser jkollhom l-imġieba għandek il-ħsieb. 259 00:12:15,450 --> 00:12:18,400 Jien Doug Lloyd u dan huwa CS50. 260 00:12:18,400 --> 00:12:20,437