1
00:00:00,000 --> 00:00:02,420
>> [Daqq tal-mużika]

2
00:00:02,420 --> 00:00:05,189

3
00:00:05,189 --> 00:00:05,980
SPEAKER: Kull dritt.

4
00:00:05,980 --> 00:00:08,540
Mela ejja nitkellmu dwar ieħor
ħaġa li tip ta 'unika biex Ċ,

5
00:00:08,540 --> 00:00:10,010
li huwa tipi ta 'data u fatturi varjabbli.

6
00:00:10,010 --> 00:00:12,340
Meta I say unika biex Ċ, I really
jfisser biss fil-kuntest ta ',

7
00:00:12,340 --> 00:00:14,470
jekk inti kont qed programmer
għal żmien twil verament,

8
00:00:14,470 --> 00:00:16,270
inti stajt probabilment mhux
ħadem ma tipi ta 'data

9
00:00:16,270 --> 00:00:18,470
jekk inti ħadthom użati moderna
lingwi ta 'programmar.

10
00:00:18,470 --> 00:00:20,432
Lingwi moderni bħall
PHP u JavaScript,

11
00:00:20,432 --> 00:00:22,640
li aħna ser tara wkoll ftit
aktar tard fil-kors,

12
00:00:22,640 --> 00:00:25,550
inti ma attwalment jkollhom jispeċifikaw
dejta tat-tip ta 'varjabbli

13
00:00:25,550 --> 00:00:26,270
meta tużah.

14
00:00:26,270 --> 00:00:28,067
>> Inti biss tiddikjaraha u tibda tuża din.

15
00:00:28,067 --> 00:00:29,900
Jekk huwa integer, huwa
taf huwa integer.

16
00:00:29,900 --> 00:00:31,960
Jekk huwa karattru, huwa
jaf huwa karattru.

17
00:00:31,960 --> 00:00:35,320
Jekk huwa ftit kliem, hija taf
huwa string, hekk imsejħa.

18
00:00:35,320 --> 00:00:37,300
>> Iżda fis-C, li hija
lingwa anzjani, għandna bżonn

19
00:00:37,300 --> 00:00:39,420
li tispeċifika d-data
tip ta 'kull varjabbli

20
00:00:39,420 --> 00:00:42,990
li noħolqu l-ewwel darba
li nużaw dak il-varjabbli.

21
00:00:42,990 --> 00:00:45,030
Allura C jiġi ma 'xi
mibnija fil-tipi ta 'data.

22
00:00:45,030 --> 00:00:46,972
U ejja nikseb familjari
ma xi wħud minn dawk.

23
00:00:46,972 --> 00:00:50,180
U allura wara aħna ser nitkellmu wkoll a
ftit dwar xi wħud mill-tipi ta 'data

24
00:00:50,180 --> 00:00:54,450
li konna bil-miktub għalik,
sabiex inti tista 'tużahom fil CS50.

25
00:00:54,450 --> 00:00:56,130
>> L-ewwel huwa int.

26
00:00:56,130 --> 00:00:59,110
Dejta tat-tip int tintuża għall-varjabbli
li se taħżen valuri numru sħiħ.

27
00:00:59,110 --> 00:01:03,210
Allura 1, 2, 3, negattiv 1, 2, 3, u l-bqija.

28
00:01:03,210 --> 00:01:05,960
Interi, li hija xi ħaġa li
għandu jżomm f'moħħu għall-kwizz,

29
00:01:05,960 --> 00:01:09,590
dejjem jieħdu erba 'bytes
tal-memorja, li huwa 32 bits.

30
00:01:09,590 --> 00:01:11,620
Hemm tmien bits fi byte.

31
00:01:11,620 --> 00:01:14,470
>> Allura dan ifisser li l-firxa ta '
valuri li integer jista 'jaħżen

32
00:01:14,470 --> 00:01:19,130
huwa limitat b'liema jistgħu joqogħdu ġewwa
32 bits jiswew ta 'informazzjoni.

33
00:01:19,130 --> 00:01:21,850
Issa kif jirriżulta,
kien twil ilu deċiż

34
00:01:21,850 --> 00:01:24,310
li aħna se jinqasam
dik il-medda ta '32 bit

35
00:01:24,310 --> 00:01:26,650
fis interi negattivi
u interi pożittivi,

36
00:01:26,650 --> 00:01:28,390
kull nofs jkollna tal-medda.

37
00:01:28,390 --> 00:01:32,230
Allura l-firxa ta 'valuri li aħna jirrappreżentaw
ma 'firxa integer minn negattiv 2

38
00:01:32,230 --> 00:01:36,520
għall-qawwa 31 għal 2 sa
l 31 poter minus 1,

39
00:01:36,520 --> 00:01:38,190
jikkawżaw inti wkoll bżonn post biex għamilhom 0.

40
00:01:38,190 --> 00:01:41,650
>> Allura bażikament nofs il-valuri possibbli
inti tista tajbin fi int huma negattivi,

41
00:01:41,650 --> 00:01:42,610
u nofshom huma pożittivi.

42
00:01:42,610 --> 00:01:47,270
U bejn wieħed u ieħor hawnhekk, dan huwa ta 'madwar negattiv
2 biljuni għal madwar pożittiv 2 biljuni.

43
00:01:47,270 --> 00:01:50,207
Agħti jew jieħu ftit mijiet ta 'miljuni.

44
00:01:50,207 --> 00:01:52,290
Allura dak hu li inti tista tajbin
fi varjabbli numru sħiħ.

45
00:01:52,290 --> 00:01:55,490
Issa irridu wkoll xi ħaġa
jissejjaħ sħiħ mhux iffirmat.

46
00:01:55,490 --> 00:01:59,220
Issa ints mhux iffirmat mhumiex
tip separat ta 'varjabbli.

47
00:01:59,220 --> 00:02:01,590
Pjuttost, iffirmata hija
dak li sejjaħ jikkwalifika.

48
00:02:01,590 --> 00:02:04,990
Jimmodifika l-informazzjoni
tip ta 'numru sħiħ ftit.

49
00:02:04,990 --> 00:02:07,850
>> U f'dan il-każ, dak iffirmata
means-- u inti tista 'ukoll

50
00:02:07,850 --> 00:02:11,530
użu ta 'tipi mhux iffirmat oħra tad-dejta,
numru sħiħ mhux l-uniku wieħed.

51
00:02:11,530 --> 00:02:15,310
Dak li effettivament ma huwa doubles
il-firxa ta 'valuri pożittivi

52
00:02:15,310 --> 00:02:19,350
li integer jista 'jieħu fuq mill
spejjeż ta 'ma tippermettilux iżjed

53
00:02:19,350 --> 00:02:21,140
inti tieħu fuq valuri negattivi.

54
00:02:21,140 --> 00:02:25,400
Mela jekk għandek numri li inti taf
se tikseb ogħla minn 2 biljuni iżda inqas

55
00:02:25,400 --> 00:02:31,280
minn 4 biljun, għal example--
li huwa 2 għall-32 power--

56
00:02:31,280 --> 00:02:33,330
inti tista 'tixtieq li tuża
l int mhux iffirmat jekk inti

57
00:02:33,330 --> 00:02:35,050
magħruf il-valur tiegħek qatt mhu se jkun negattiv.

58
00:02:35,050 --> 00:02:37,216
>> Int ser kultant ikollhom
użat għall-varjabbli mhux iffirmat

59
00:02:37,216 --> 00:02:39,460
fil CS50, u huwa għalhekk nsemmi hawnhekk.

60
00:02:39,460 --> 00:02:43,830
Iżda għal darb'oħra, il-firxa ta 'valuri li inti
jista 'jirrappreżenta bi sħiħ mhux iffirmat

61
00:02:43,830 --> 00:02:48,240
li t numru sħiħ regolari, huma 0
2 għall-qawwa 32 minus 1,

62
00:02:48,240 --> 00:02:50,840
jew madwar 0-4000000000.

63
00:02:50,840 --> 00:02:53,730
Allura inti ħadthom effettivament irdoppja l
firxa pożittiv li inti tista tajbin,

64
00:02:53,730 --> 00:02:56,270
imma inti ħadthom rrinunzjaw kollha
il-valuri negattivi.

65
00:02:56,270 --> 00:03:00,040
>> Issa bħala twarrib, iffirmata
mhuwiex l-uniku jikkwalifika

66
00:03:00,040 --> 00:03:01,790
li nistgħu tara għalik
tipi ta 'data varjabbli.

67
00:03:01,790 --> 00:03:05,779
Hemm ukoll affarijiet imsejħa
qasir u twil u const.

68
00:03:05,779 --> 00:03:07,820
Const Ser naraw ftit
Wara ftit fil-kors.

69
00:03:07,820 --> 00:03:10,830
Qasir, aħna probabbilment mhux se.

70
00:03:10,830 --> 00:03:12,830
>> Iżda biss jafu li hemm
huma kwalifiki oħra.

71
00:03:12,830 --> 00:03:14,080
Mhux iffirmat mhuwiex l-uniku wieħed.

72
00:03:14,080 --> 00:03:16,596
Imma hija l-unika waħda aħna qed
ser jitkellmu dwar id-dritt issa.

73
00:03:16,596 --> 00:03:17,310
Allura id-dritt.

74
00:03:17,310 --> 00:03:18,393
Allura konna koperti interi.

75
00:03:18,393 --> 00:03:19,200
Xi jmiss?

76
00:03:19,200 --> 00:03:20,130
>> Chars.

77
00:03:20,130 --> 00:03:23,620
Allura Chars huma użati għall-varjabbli
li se taħżen karattri uniku.

78
00:03:23,620 --> 00:03:24,850
Char huwa qasir għall-karattru.

79
00:03:24,850 --> 00:03:27,870
U xi kultant inti tista 'tisma
nies jippronunzja bħala karozza.

80
00:03:27,870 --> 00:03:32,020
>> Allura karattri dejjem jibdew waħda
byte ta 'memorja, li huwa biss 8 bits.

81
00:03:32,020 --> 00:03:35,700
Allura dan ifisser li dawn jistgħu biss tajbin
valuri fil-firxa ta negattiva 2

82
00:03:35,700 --> 00:03:42,430
is-seba 'enerġija, jew negattiv 128,
2 għas-7 poter minus 1, jew 127.

83
00:03:42,430 --> 00:03:45,710
>> Grazzi għall ASCII, kien
twil ilu iddeċidew mod

84
00:03:45,710 --> 00:03:50,805
Mappa dawn in-numri pożittivi minn
0-127 diversi karattri

85
00:03:50,805 --> 00:03:52,182
li kollha jeżistu fuq it-tastiera tagħna.

86
00:03:52,182 --> 00:03:54,640
Allura kif Ser naraw aktar tard fil
il-kors, u inti probabilment

87
00:03:54,640 --> 00:03:57,700
jaslu għal jimmemorizza f'xi
punt, il-kapital A, għal example--

88
00:03:57,700 --> 00:04:00,732
il-kapital karattru A--
mapep għan-numru 65.

89
00:04:00,732 --> 00:04:02,940
U r-raġuni għal dan hi
għaliex dan huwa dak li huwa

90
00:04:02,940 --> 00:04:05,490
ġie assenjat mill-istandard ASCII.

91
00:04:05,490 --> 00:04:07,850
>> Zghar A hija 97.

92
00:04:07,850 --> 00:04:11,900
Il-karattru 0 meta inti
fil-fatt tip-karattru, ma

93
00:04:11,900 --> 00:04:13,532
tirrappreżenta n-numru żero, huwa 48.

94
00:04:13,532 --> 00:04:15,240
Int ser ikollok jitgħallmu ftit
minn dawn kif tmur.

95
00:04:15,240 --> 00:04:17,990
U tkun taf ċertament ħafna għall-ħtieġa
minnhom ftit aktar tard fil CS50.

96
00:04:17,990 --> 00:04:20,450

97
00:04:20,450 --> 00:04:23,390
>> It-tip ewlieni data jmiss
f'wiċċ l-ilma punt numri.

98
00:04:23,390 --> 00:04:26,100
Allura floating numri punt huma
magħrufa wkoll bħala numri reali.

99
00:04:26,100 --> 00:04:28,850
Huma qed bażikament numri li
għandhom punt deċimali fihom.

100
00:04:28,850 --> 00:04:33,360
Floating valuri tal-punti
bħal interi huma wkoll

101
00:04:33,360 --> 00:04:36,090
li tinsab fi żmien 4 bytes ta 'memorja.

102
00:04:36,090 --> 00:04:37,580
Issa hemm ebda chart hawn.

103
00:04:37,580 --> 00:04:40,890
M'hemm l-ebda linja numru, għaliex
jiddeskrivi l-firxa ta 'float

104
00:04:40,890 --> 00:04:44,550
mhuwiex eżattament ċar jew intuwittivi.

105
00:04:44,550 --> 00:04:47,350
>> Biżżejjed ngħid lilek
jkollhom 32 bits biex jaħdmu ma '.

106
00:04:47,350 --> 00:04:49,730
U jekk għandek numru
bħal pi, li għandha

107
00:04:49,730 --> 00:04:55,510
parti integer 3, u floating
punt parti, jew parti deċimali 0.14159,

108
00:04:55,510 --> 00:04:58,735
u l-bqija, inti jeħtieġ li tkun
jistgħu jirrappreżentaw kollha it--

109
00:04:58,735 --> 00:05:02,420
il-parti numru sħiħ u l-parti deċimali.

110
00:05:02,420 --> 00:05:04,550
>> Allura dak li taħseb li jista 'jfisser?

111
00:05:04,550 --> 00:05:08,180
Ħaġa waħda hija li jekk l-deċimali
parti gets itwal u itwal,

112
00:05:08,180 --> 00:05:10,660
jekk ikolli kbir ħafna
parti numru sħiħ, I ma jista

113
00:05:10,660 --> 00:05:13,090
tkun tista 'tkun preċiża
mal-parti deċimali.

114
00:05:13,090 --> 00:05:15,280
U li verament il-
limitazzjoni ta 'float.

115
00:05:15,280 --> 00:05:17,229
>> Sufruni jkollhom problema preċiżjoni.

116
00:05:17,229 --> 00:05:19,270
Aħna biss 32 bits għal
jaħdmu ma ', sabiex inkunu nistgħu biss

117
00:05:19,270 --> 00:05:22,510
jkunu tant preċiżi ma 'parti deċimali tagħna.

118
00:05:22,510 --> 00:05:27,300
Ma nistgħux neċessarjament ikollhom deċimali
parti preċiżi għal 100 jew 200 numri,

119
00:05:27,300 --> 00:05:29,710
għaliex aħna biss
32 bits biex jaħdmu ma '.

120
00:05:29,710 --> 00:05:31,590
Allura dak limitazzjoni ta 'float.

121
00:05:31,590 --> 00:05:33,590
>> Issa fortunatament hemm
tip ta 'data oħra msejħa

122
00:05:33,590 --> 00:05:36,530
doppja, li xi ftit
jittratta din il-problema.

123
00:05:36,530 --> 00:05:39,980
Doubles, bħal sufruni, huma wkoll użati biex
taħżen numri reali, jew punt floating

124
00:05:39,980 --> 00:05:40,840
valuri.

125
00:05:40,840 --> 00:05:44,340
Id-differenza hija li
jirdoppja huma preċiżjoni doppja.

126
00:05:44,340 --> 00:05:48,177
Huma jistgħu joqogħdu 64 bits ta
data, jew tmien bytes.

127
00:05:48,177 --> 00:05:49,010
Xi tfisser?

128
00:05:49,010 --> 00:05:51,801
Ukoll, dan ifisser li nistgħu jkun hemm ħafna aktar
preċiż mal-punt deċimali.

129
00:05:51,801 --> 00:05:54,830
Minflok ma jkollhom pi għal sebgħa
postijiet forsi, bil-float,

130
00:05:54,830 --> 00:05:56,710
nistgħu forsi għandna hija li 30 postijiet.

131
00:05:56,710 --> 00:05:59,824
Jekk dan huwa importanti, inti tista 'tixtieq
li jużaw doppju minflok ta 'float.

132
00:05:59,824 --> 00:06:01,740
Bażikament, jekk int
jaħdmu fuq xi ħaġa fejn

133
00:06:01,740 --> 00:06:06,540
jkollha post deċimali verament twila
u ħafna ta 'preċiżjoni hija importanti,

134
00:06:06,540 --> 00:06:08,630
inti probabilment tixtieq li
jużaw overfloat doppja.

135
00:06:08,630 --> 00:06:11,250
Issa għal ħafna tax-xogħol tiegħek fil
CS50, float għandha tkun biżżejjed.

136
00:06:11,250 --> 00:06:15,340
Iżda nafu li jirdoppja jeżistu bħala
mod biex kemmxejn tittratta l-preċiżjoni

137
00:06:15,340 --> 00:06:20,980
problema billi giving you extra 32
bits biex jaħdmu ma 'għal numri tiegħek.

138
00:06:20,980 --> 00:06:23,650
>> Issa dan mhuwiex tip ta 'data.

139
00:06:23,650 --> 00:06:24,390
Din hija tip.

140
00:06:24,390 --> 00:06:25,340
U huwa msejjaħ bla effett.

141
00:06:25,340 --> 00:06:27,506
U jien jitkellem dwar dan
hawnhekk għaliex aħna ħadthom probabbilment

142
00:06:27,506 --> 00:06:29,520
bbenefikawx għal xi ftit drabi diġà fil CS50.

143
00:06:29,520 --> 00:06:32,020
U inti tista 'tkun mintix
dak li huwa kollha madwar.

144
00:06:32,020 --> 00:06:33,390
>> Allura null huwa tip.

145
00:06:33,390 --> 00:06:34,097
Hija ma jeżistu.

146
00:06:34,097 --> 00:06:35,180
Iżda mhuwiex tip ta 'data.

147
00:06:35,180 --> 00:06:39,350
>> Aħna ma tistax toħloq varjabbli ta 'tip
null u tassenja valur lilha.

148
00:06:39,350 --> 00:06:42,519
Iżda funzjonijiet, per eżempju,
jista 'jkollhom tip ta' ritorn bla effett.

149
00:06:42,519 --> 00:06:45,060
Bażikament, jekk inti tara funzjoni
li għandha tip ritorn null,

150
00:06:45,060 --> 00:06:46,970
dan ifisser li ma jerġax lura valur.

151
00:06:46,970 --> 00:06:49,440
Tista 'taħseb ta' komuni
funzjoni li konna użati s'issa

152
00:06:49,440 --> 00:06:52,780
fil CS50 li ma jerġax lura valur?

153
00:06:52,780 --> 00:06:54,700
>> Printf hija waħda.

154
00:06:54,700 --> 00:06:56,820
Printf ma attwalment
ritorn xejn għalik.

155
00:06:56,820 --> 00:06:59,850
Hija prints xi ħaġa li l-
iskrin, u huwa bażikament

156
00:06:59,850 --> 00:07:01,650
effett sekondarju ta 'dak printf ma.

157
00:07:01,650 --> 00:07:03,620
Iżda dan ma jtik valur lura.

158
00:07:03,620 --> 00:07:08,419
Inti ma jaqbdu l-riżultat u jaħżnu
dan f'xi varjabbli jużah aktar tard.

159
00:07:08,419 --> 00:07:10,710
Hija biss prints xi ħaġa li
l-iskrin u inti qed isir.

160
00:07:10,710 --> 00:07:14,360
>> Allura aħna ngħidu li printf
hija funzjoni null.

161
00:07:14,360 --> 00:07:16,450
Dan jirritorna xejn.

162
00:07:16,450 --> 00:07:18,580
>> Il-lista perimetru ta '
funzjoni tista 'wkoll tkun nulla.

163
00:07:18,580 --> 00:07:21,410
U inti stajt wkoll meqjus li
pjuttost ftit fil CS50 wisq.

164
00:07:21,410 --> 00:07:22,300
Null prinċipali Int.

165
00:07:22,300 --> 00:07:23,260
Does li ring qanpiena?

166
00:07:23,260 --> 00:07:24,080

167
00:07:24,080 --> 00:07:27,220
Bażikament dak li tfisser hija li
prinċipali ma tieħu xi parametri.

168
00:07:27,220 --> 00:07:29,520
M'hemm l-ebda argument li
jiksbu għadda fis prinċipali.

169
00:07:29,520 --> 00:07:32,780
Issa aktar tard Ser naraw li hemm
mod li jgħaddu argumenti fis prinċipali,

170
00:07:32,780 --> 00:07:36,189
iżda s'issa dak li konna
tidher hija nulla prinċipali int.

171
00:07:36,189 --> 00:07:37,730
Main biss ma tieħu ebda argument.

172
00:07:37,730 --> 00:07:40,236
U hekk aħna jispeċifikaw li billi qal null.

173
00:07:40,236 --> 00:07:42,110
Aħna biss qed ħafna
espliċitu dwar il-fatt

174
00:07:42,110 --> 00:07:44,430
li dan ma jieħux ebda argument.

175
00:07:44,430 --> 00:07:47,160
>> Allura għal issa, huwa biżżejjed li jiġi
jgħidu li null bażikament

176
00:07:47,160 --> 00:07:50,789
għandhom biss iservu bħala placeholder
għalik bħala taħseb dwar kif xejn.

177
00:07:50,789 --> 00:07:52,080
Mhuwiex verament tagħmel xejn.

178
00:07:52,080 --> 00:07:53,550
M'hemm l-ebda valur tar-ritorn hawn.

179
00:07:53,550 --> 00:07:54,770
M'hemm l-ebda parametri hawn.

180
00:07:54,770 --> 00:07:55,709
Huwa bla effett.

181
00:07:55,709 --> 00:07:57,250
Huwa ftit aktar kumplessa minn dik.

182
00:07:57,250 --> 00:08:00,640
Iżda dan għandu jkun biżżejjed għall
aħjar il-parti tal-kors.

183
00:08:00,640 --> 00:08:05,010
U nisperaw issa għandek ftit
daqsxejn aktar ta 'kunċett ta' dak li huwa null.

184
00:08:05,010 --> 00:08:08,460
>> Għalhekk dawn huma l-ħames tipi tkun taf
jiltaqgħu li huma mibnija fil lill C.

185
00:08:08,460 --> 00:08:10,670
Iżda fil CS50 aħna għandna wkoll librerija.

186
00:08:10,670 --> 00:08:13,550
CS50.h, li inti tista 'tinkludi.

187
00:08:13,550 --> 00:08:15,930
U li ser jagħtik
b'żewġ tipi addizzjonali

188
00:08:15,930 --> 00:08:18,280
li inti probabilment tkun kapaċi
għall-użu fuq inkarigi tiegħek,

189
00:08:18,280 --> 00:08:21,210
jew tax-xogħol ġusti ġeneralment programmazzjoni.

190
00:08:21,210 --> 00:08:23,030
>> L-ewwel minn dawn huwa BOOL.

191
00:08:23,030 --> 00:08:26,780
Allura dejta tat-tip Boolean,
BOOL, huwa użat għall-varjabbli

192
00:08:26,780 --> 00:08:28,114
li se taħżen valur Boolean.

193
00:08:28,114 --> 00:08:29,863
Jekk inti stajt qatt semgħu
dan it-terminu qabel, inti

194
00:08:29,863 --> 00:08:31,960
tista 'taf li Boolean
valur huwa kapaċi biss

195
00:08:31,960 --> 00:08:34,440
jesgħu żewġ valuri distinti differenti.

196
00:08:34,440 --> 00:08:35,872
Vera u falza.

197
00:08:35,872 --> 00:08:37,580
Issa dan jidher pretty
fundamentali, id-dritt?

198
00:08:37,580 --> 00:08:40,496
Huwa tip ta 'sorpriża li din
ma jeżistix fil C kif huwa mibni.

199
00:08:40,496 --> 00:08:42,640
U f'lingwi moderni ħafna,
Naturalment, Booleans

200
00:08:42,640 --> 00:08:45,390
huma tip data default standard.

201
00:08:45,390 --> 00:08:47,192
Iżda fis-C, dawn qed attwalment le.

202
00:08:47,192 --> 00:08:48,400
Iżda aħna ve maħluqa dan għalik.

203
00:08:48,400 --> 00:08:51,910
Mela jekk inti qatt bżonn biex joħolqu
varjabbli li tip huwa BOOL,

204
00:08:51,910 --> 00:08:55,230
biss kun żgur li #include CS50.h
fil-bidu tal-programm tiegħek,

205
00:08:55,230 --> 00:08:57,800
u tkun taf tkun kapaċi joħolqu
varjabbli tat-tip BOOL.

206
00:08:57,800 --> 00:09:02,095
>> Jekk tinsa #include CS50.h, u
tibda tuża varjabbli Boolean tat-tip,

207
00:09:02,095 --> 00:09:04,970
inti tista 'tiltaqa' xi problemi
meta int kumpilazzjoni program tiegħek.

208
00:09:04,970 --> 00:09:06,490
Hekk biss tkun fuq il-lookout għal dan.

209
00:09:06,490 --> 00:09:11,180
U forsi inti tista 'sempliċement tiffissa l-
problemi billi lira inkluż CS50.h.

210
00:09:11,180 --> 00:09:14,590
>> It-tip ewlieni data oħra li aħna
jipprovdu għalik fil-librerija CS50

211
00:09:14,590 --> 00:09:15,670
huwa string.

212
00:09:15,670 --> 00:09:17,130
Allura dak li huwa string?

213
00:09:17,130 --> 00:09:18,520
Strings huma verament biss kliem.

214
00:09:18,520 --> 00:09:20,000
Huma qed kollezzjonijiet ta 'karattri.

215
00:09:20,000 --> 00:09:20,640
Huma qed kliem.

216
00:09:20,640 --> 00:09:21,390
Huma qed sentenzi.

217
00:09:21,390 --> 00:09:22,480
Huma qed paragrafi.

218
00:09:22,480 --> 00:09:25,850
Jista 'jkun kotba sħaħ, anke.

219
00:09:25,850 --> 00:09:29,690
>> Qasir ħafna biex twil ħafna
serje ta 'karattri.

220
00:09:29,690 --> 00:09:34,310
Jekk għandek bżonn tuża kordi,
per eżempju, biex jaħżnu kelma,

221
00:09:34,310 --> 00:09:37,609
biss kun żgur li tinkludi CS50.h
fil-bidu tal-programm tiegħek

222
00:09:37,609 --> 00:09:38,900
sabiex inti tista 'tuża t-tip sekwenza.

223
00:09:38,900 --> 00:09:43,910
U allura inti tista 'toħloq varjabbli
tip ta 'data li hija sekwenza.

224
00:09:43,910 --> 00:09:46,160
Issa aktar tard fil-kors,
Ser naraw ukoll li dan huwa

225
00:09:46,160 --> 00:09:47,752
mhux l-istorja sħiħa, lanqas.

226
00:09:47,752 --> 00:09:49,460
Aħna ser tiltaqa affarijiet
imsejħa strutturi,

227
00:09:49,460 --> 00:09:54,249
li jippermetti li inti grupp liema jista 'jkun
integer u string fil unità waħda.

228
00:09:54,249 --> 00:09:56,290
U nistgħu nużaw li għal
xi skop, li jistgħu

229
00:09:56,290 --> 00:09:57,750
jaqgħu fil handy aktar tard fil-kors.

230
00:09:57,750 --> 00:09:59,500
>> U aħna ser jitgħallmu wkoll
dwar it-tipi definiti,

231
00:09:59,500 --> 00:10:01,720
li jippermettu li inti toħloq
tipi ta 'data tiegħek.

232
00:10:01,720 --> 00:10:03,060
Aħna ma bżonn ninkwetaw
dwar li għal issa.

233
00:10:03,060 --> 00:10:04,550
Iżda biss jafu li dan huwa
xi ħaġa fuq l-orizzont,

234
00:10:04,550 --> 00:10:07,633
li hemm ħafna aktar għal dan kollu
Ħaġa tip minn jien tghidlek biss

235
00:10:07,633 --> 00:10:08,133
issa.

236
00:10:08,133 --> 00:10:10,591
Allura issa li konna tgħallimna
ftit dwar id-data bażika

237
00:10:10,591 --> 00:10:14,230
tipi u tip ta 'data CS50, ejja
jitkellmu dwar kif taħdem ma 'varjabbli

238
00:10:14,230 --> 00:10:18,530
u jinħolqu minnhom jużaw dawn
tipi ta 'data fil-programmi tagħna.

239
00:10:18,530 --> 00:10:22,670
Jekk inti tixtieq li toħloq varjabbli,
kull ma għandek bżonn tagħmel huwa żewġ affarijiet.

240
00:10:22,670 --> 00:10:24,147
>> L-ewwel, inti għandek bżonn biex tagħtiha tip.

241
00:10:24,147 --> 00:10:26,230
It-tieni ħaġa li għandek bżonn
tagħmel hu tagħtiha isem.

242
00:10:26,230 --> 00:10:28,740
Ladarba inti ghamilt dan u slapped
virgola fi tmiem dak il-linja,

243
00:10:28,740 --> 00:10:29,830
inti stajt ħolqot varjabbli.

244
00:10:29,830 --> 00:10:32,370
>> Allura hawnhekk żewġ eżempji.

245
00:10:32,370 --> 00:10:35,744
Numru int; ittra char ;.

246
00:10:35,744 --> 00:10:36,660
Liema kienu I għamlu hawn?

247
00:10:36,660 --> 00:10:38,110
Stajt ħolqot żewġ varjabbli.

248
00:10:38,110 --> 00:10:40,190
>> L-ewwel, il-varjabbli tal-
isem huwa numru.

249
00:10:40,190 --> 00:10:44,830
U n-numru huwa kapaċi li jżommu numru sħiħ
tip valuri, minħabba tip tagħha huwa int.

250
00:10:44,830 --> 00:10:48,040
L-ittra huwa varjabbli ieħor
li tista 'żżomm karattri

251
00:10:48,040 --> 00:10:50,240
minħabba tip ta 'data tagħha hija char.

252
00:10:50,240 --> 00:10:51,772
>> Pretty sempliċi, id-dritt?

253
00:10:51,772 --> 00:10:53,480
Jekk issib ruħek
f'sitwazzjoni fejn

254
00:10:53,480 --> 00:10:56,250
għandek bżonn biex joħolqu multipli
varjabbli tal-istess tip,

255
00:10:56,250 --> 00:10:58,740
għandek bżonn biss li tispeċifika
l-isem tip darba.

256
00:10:58,740 --> 00:11:01,600
Imbagħad biss lista kif ħafna fatturi varjabbli
ta 'dak it-tip kif għandek bżonn.

257
00:11:01,600 --> 00:11:04,230
>> So I jistgħu pereżempju, hawn
f'dan tielet linja ta 'kodiċi,

258
00:11:04,230 --> 00:11:07,420
jgħidu għoli int ;, linja ġdida.

259
00:11:07,420 --> 00:11:08,291
Wisa int ;.

260
00:11:08,291 --> 00:11:09,290
U li tkun taħdem wisq.

261
00:11:09,290 --> 00:11:12,039
I d xorta jiksbu żewġ varjabbli imsejħa
għoli u wisa, li kull wieħed minnhom

262
00:11:12,039 --> 00:11:12,730
huwa integer.

263
00:11:12,730 --> 00:11:16,970
Imma jien jitħallew, affarijiet li sintassi C,
tikkonsolidaha linja waħda.

264
00:11:16,970 --> 00:11:20,230
Għoli int, wisa; Huwa l-istess ħaġa.

265
00:11:20,230 --> 00:11:23,900
Stajt ħolqot żewġ varjabbli, wieħed imsejħa
għoli wieħed imsejjaħ wisa ', it-tnejn li

266
00:11:23,900 --> 00:11:26,730
huma kapaċi li jżommu
Valuri tip numru sħiħ.

267
00:11:26,730 --> 00:11:30,920
>> Bl-istess mod hawnhekk, I jistgħu joħolqu tliet
f'wiċċ l-ilma valuri tal-punti mill-ewwel.

268
00:11:30,920 --> 00:11:33,350
I tista 'forsi toħloq varjabbli
imsejħa għerq kwadrat tal 2--

269
00:11:33,350 --> 00:11:35,766
li preżumibbilment se eventwalment
żomm il-point-- f'wiċċ l-ilma

270
00:11:35,766 --> 00:11:39,222
li rappreżentazzjoni tal-kwadru
għerq ta 2-- għerq kwadrat ta '3, u pi.

271
00:11:39,222 --> 00:11:41,180
I seta 'jsir dan
fuq tliet linji separati.

272
00:11:41,180 --> 00:11:47,690
Float, għerq kwadrat 2; Float għerq ikkwadrat
3; float pi; u li tkun taħdem wisq.

273
00:11:47,690 --> 00:11:50,590
>> Iżda għal darb'oħra, I tista 'biss jikkonsolida
dan fis-linja waħda tal-kodiċi.

274
00:11:50,590 --> 00:11:54,050
Tagħmel affarijiet ftit
iqsar, mhux bħala clunky.

275
00:11:54,050 --> 00:11:57,259
>> Issa b'mod ġenerali, huwa disinn tajjeb biss
tiddikjara varjabbli meta jkollok bżonnha.

276
00:11:57,259 --> 00:11:59,050
U aħna ser nitkellmu ftit
ftit aktar dwar dan

277
00:11:59,050 --> 00:12:00,945
aktar tard fil-kors
meta niddiskutu ambitu.

278
00:12:00,945 --> 00:12:03,320
Allura mhux bilfors li
joħolqu kollha ta 'varjabbli tiegħek

279
00:12:03,320 --> 00:12:05,990
fil-bidu tal-programm, li
xi nies jistgħu għamlu l-passat,

280
00:12:05,990 --> 00:12:08,700
jew kienet ċertament komuni ħafna
prattika kodifikazzjoni ħafna snin ilu

281
00:12:08,700 --> 00:12:11,700
meta jaħdmu ma C. inti tista 'biss
tixtieq li toħloq dritt varjabbli meta

282
00:12:11,700 --> 00:12:13,140
jkollok bżonnha.

283
00:12:13,140 --> 00:12:13,640
Kull dritt.

284
00:12:13,640 --> 00:12:15,150
Allura konna maħluqa varjabbli.

285
00:12:15,150 --> 00:12:16,790
Kif nistgħu jużawhom?

286
00:12:16,790 --> 00:12:18,650
Wara aħna tiddikjara
varjabbli, ma kellniex bżonn

287
00:12:18,650 --> 00:12:21,237
biex tispeċifika t-tip tad-data
ta 'dak il-varjabbli aktar.

288
00:12:21,237 --> 00:12:24,070
Fil-fatt, jekk inti tagħmel dan, inti tista
tispiċċa ma 'xi konsegwenzi stramb

289
00:12:24,070 --> 00:12:25,490
li aħna ser tip ta 'tleqqija fuq għal issa.

290
00:12:25,490 --> 00:12:27,365
Iżda huwa biżżejjed li jingħad,
affarijiet stramb sejrin

291
00:12:27,365 --> 00:12:30,740
biex tibda jiġri jekk inti involontarjament
mill-ġdid tiddikjara varjabbli bl-istess isem

292
00:12:30,740 --> 00:12:32,210
aktar u aktar.

293
00:12:32,210 --> 00:12:33,882
>> So here I jkollhom erba 'linji ta' kodiċi.

294
00:12:33,882 --> 00:12:36,090
UI għandhom ftit
Kummenti hemm biss jindikaw

295
00:12:36,090 --> 00:12:37,840
dak li qed jiġri fuq
kull linja biss biex jgħinu

296
00:12:37,840 --> 00:12:40,520
ikollok jinsab x'inhu għaddej.

297
00:12:40,520 --> 00:12:41,520
Numru hekk int ;.

298
00:12:41,520 --> 00:12:42,520
Inti raw li qabel.

299
00:12:42,520 --> 00:12:44,000
Li dikjarazzjoni varjabbli.

300
00:12:44,000 --> 00:12:46,670
>> Stajt issa ħolqot varjabbli
imsejħa numru li l-

301
00:12:46,670 --> 00:12:48,970
kapaċi li jżomm valuri tat-tip numru sħiħ.

302
00:12:48,970 --> 00:12:50,210
Stajt ddikjarat dan.

303
00:12:50,210 --> 00:12:53,770
>> Il-linja li jmiss jien tassenja
valur li numru.

304
00:12:53,770 --> 00:12:54,992
Numru ugwali 17.

305
00:12:54,992 --> 00:12:55,950
Dak li qed jiġri hemmhekk?

306
00:12:55,950 --> 00:12:58,880
Jien tqegħid tal-numru 17
ġewwa ta 'dak il-varjabbli.

307
00:12:58,880 --> 00:13:02,760
>> Mela jekk jien qatt mbagħad jistampa dak
il-kontenut tal-għadd huma aktar tard,

308
00:13:02,760 --> 00:13:04,030
dawn ser tell me huwa 17.

309
00:13:04,030 --> 00:13:07,030
Hekk stajt iddikjarat varjabbli,
u mbagħad stajt assenjat lilha.

310
00:13:07,030 --> 00:13:10,570
>> Aħna tista 'tirrepeti l-proċess
għal darb'oħra bl-ittra char ;.

311
00:13:10,570 --> 00:13:11,640
Li dikjarazzjoni.

312
00:13:11,640 --> 00:13:14,010
Ittra ugwali kapital
H. Li assenjazzjoni.

313
00:13:14,010 --> 00:13:16,030
Pretty sempliċi, wisq.

314
00:13:16,030 --> 00:13:18,319
>> Issa dan il-proċess jista
jidhru tip ta 'iblah.

315
00:13:18,319 --> 00:13:20,110
Għaliex aħna tagħmel dan
f'żewġ linji ta 'kodiċi?

316
00:13:20,110 --> 00:13:21,401
Hemm mod aħjar biex tagħmel dan?

317
00:13:21,401 --> 00:13:22,250
Fil-fatt, hemm.

318
00:13:22,250 --> 00:13:24,375
Kultant inti tista 'tara
dan jissejjaħ inizjalizzazzjoni.

319
00:13:24,375 --> 00:13:28,446
Huwa meta inti tiddikjara varjabbli
u tassenja valur fl-istess ħin.

320
00:13:28,446 --> 00:13:30,320
Dan huwa attwalment pretty
ħaġa komuni li tagħmel.

321
00:13:30,320 --> 00:13:32,870
Meta inti toħloq varjabbli, inti normalment
tixtieq li jkollha xi valur bażiku.

322
00:13:32,870 --> 00:13:34,330
Anki jekk huwa 0 jew xi ħaġa.

323
00:13:34,330 --> 00:13:36,180
Inti biss għandek tagħtiha valur.

324
00:13:36,180 --> 00:13:38,360
>> Tista 'initialize varjabbli.

325
00:13:38,360 --> 00:13:42,320
Int numru ugwali 17 huwa l-istess bħal
l-ewwel żewġ linji ta 'kodiċi up hawn fuq.

326
00:13:42,320 --> 00:13:46,829
Ittra Char ugwali h huwa l-istess bħall-
tielet u r-raba 'linji ta' kodiċi ta 'hawn fuq.

327
00:13:46,829 --> 00:13:49,620
L-takeaway aktar importanti hawnhekk
meta aħna qed tiddikjara u tassenja

328
00:13:49,620 --> 00:13:51,740
varjabbli huwa wara konna
ddikjarat li, avviż

329
00:13:51,740 --> 00:13:53,700
Jien ma jużawx dejta tat-tip ġdid.

330
00:13:53,700 --> 00:13:57,916
Jien ma tgħid int numru ugwali 17 dwar
it-tieni linja ta 'kodiċi, per eżempju.

331
00:13:57,916 --> 00:13:59,290
Jien biss qal numru ugwali 17.

332
00:13:59,290 --> 00:14:02,537
>> Għal darb'oħra, jerġgħu tiddikjara varjabbli wara
inti stajt diġà ddikjarat dan jista 'jwassal

333
00:14:02,537 --> 00:14:03,620
għal xi konsegwenza stramb.

334
00:14:03,620 --> 00:14:05,950
Hekk biss tkun attenta ta 'dak.

335
00:14:05,950 --> 00:14:06,660
>> Jien Doug Lloyd.

336
00:14:06,660 --> 00:14:08,870
U dan huwa CS50.

337
00:14:08,870 --> 00:14:10,499