txheem
Цikl rau python i lub voj voog thaum - nqe lus software lus, xws li: iteration operators, ciatej no rov code muab tus lej sij hawm.
Цикл Rau — сintaxis
Raws li tau piav qhia, csuav nrog rau hauv Python yog ib qho iterator raws liй rau lub voj voogqhia tias yog leejtwg. yog nws ua los ntawm cov ntsiab lus и daim ntawv teev, Lo lus yuam sij thiab lwm yam yam khoom siv tau.
Ib lub voj hauv Python pib nrog rau lo lus tseem ceeb, ua raws li lub npe sib txawv ntawm qhov tsis sib xws uas khaws cov nqi ntawm cov khoom tom ntej hauv cov kab ke muab. General syntax rau ... nyob rau hauv python zoo li no:
rau hauv:lwm:
cheebtsam “sequences” muaj npe ib tug dhau ib lub voj voog hloov pauv. Los yog theej, variable ntsiab lus rau xws cov ntsiab lus. Rau sawv daws ntawm lawv "action" yog ua.
Ib qho yooj yim rau voj hauv Python nrog ib qho piv txwv tshwj xeeb:
>>> languages = ["C", "C++", "Perl", "Python"] >>> rau x hauv hom lus: ... print(x) ... C C++ Perl Python >>>
Lwm qhov thaiv yog tshwj xeebth. Yog ib programmerыua hauj lwm с Perl paubы nrog nws, uas rau cov neeg sib tham с C thiab C++ — qhov no yog kev tsim kho tshiab. Semanically nws zog тzoo ib yam hos voj.
Tsuas yog ua tiav thaum lub voj tsis "tshem" los ntawm cov lus hais tawm. Ntawd yog, nws tsuas yog ua tiav tom qab tag nrho cov ntsiab lus tau dhau los ntawm cov txheej txheem teev tseg.
Rhuav tus neeg teb xov tooj hauv python - so
Yog hais tias qhov kev pab cuam muaj ib lub voj tsim nyog kev cuam tshuamlub tawg nqe lus, he tiavnws musthiab kev pab cuam ntws yuav contyuav tsum tau tsis muaj ua kom los ntawm lwm tus.
Ntau zaus rhuav cov kab lus hauv pythonuyutsya nrog cov lus hais.
edibles = ["chops", "dumplings","eg","nuts"] rau zaub mov hauv edibles: yog zaub mov == "dumplings": print("Kuv tsis noj dumplings!") tawg print("Zoo, qab "+ zaub mov) lwm tus: luam tawm ("Nws zoo uas tsis muaj dumplings!") luam tawm (" noj hmo dhau lawm.")Yog tias koj khiav qhov chaws no, koj tau txais cov txiaj ntsig hauv qab no:
Zoo heev, delicious chops. Kuv tsis noj dumplings! Noj hmo lawm.
Peb tshem "dumplings" los ntawm cov npe ntawm cov ntaub ntawv uas twb muaj lawm thiab tau txais:
Zoo heev, qab chops Zoo heev, qab qe Zoo heev, qab txiv ntoo Zoo yam tsis muaj dumplings! Noj hmo lawm.
python hla tus neeg teb xov tooj - txuas ntxiv mus
Cia peb hais tias tus neeg siv txoj kev tsis txaus siab rau cov khoom zoo li no tsis yog qhov zoo kawg nkaus kom tso tseg lawv cov khoom noj. Yog li ntawd, lub voj txuas ntxiv nrog tus neeg teb xov tooj continue. Cov ntawv hauv qab no siv cov lus qhia continue, mus txuas ntxiv iterating los ntawm cov npe ntawm "dumpling contact".
edibles = ["chops", "dumplings","eggs","nuts"] rau zaub mov hauv edibles: yog zaub mov == "dumplings": print("Kuv tsis noj dumplings!") txuas ntxiv print("Zoo, qab" + zaub mov) # qhov no yuav yog code rau kev lom zem zaub mov :-) lwm tus: print("Kuv ntxub dumplings!") print(" noj hmo dhau lawm.")Cov kab hauv qab:
Zoo heev, delicious chops. Kuv tsis noj dumplings! Zoo heev, qab qe Zoo, qab txiv ntoo Kuv ntxub dumplings! Noj hmo lawm.
Iterating tshaj cov npe nrog ntau yam () muaj nuj nqi
Yog tias koj xav nkag mus rau qhov ntsuas ntawm cov npe, nws tsis paub meej tias yuav siv lub voj voog rau lub hom phiaj no li cas. Nws tuaj yeem nkag mus rau tag nrho cov ntsiab lus, tab sis lub ntsiab lus ntsuas yuav nyob twj ywm tsis tau. Txawm li cas los xij, muaj ib txoj hauv kev rau kev nkag mus rau ob lub ntsiab qhov ntsuas thiab lub caij nws tus kheej. Rau lub hom phiaj no, kev ua haujlwm yog siv range() ua ke nrog qhov ntev ua haujlwm len():
fibonacci = [0,1,1,2,3,5,8,13,21] rau i in range(len(fibonacci)): print(i,fibonacci[i])
Tau:
0 0 1 1 2 1 3 2 4 3 5 5 6 8 7 13 8 21 XNUMX XNUMX XNUMX XNUMX XNUMX
Nco ntsoov! Thaum thov
len()кlistortuple, tus naj npawb ntawm cov ntsiab lus ntawm qhov muab ua ntu zus tau txais.
Nyuaj ntawm iterating tshaj cov npe
Thaum iterating tshaj ib daim ntawv teev npe, nws raug nquahu kom tsis txhob sau cov dynamics hauv lub voj voog lub cev. Txhawm rau kom meej meej, peb tuaj yeem muab cov kev xaiv hauv qab no:
cov xim = ["liab"] rau kuv hauv cov xim: yog kuv == "liab": xim += ["dub"] yog kuv == "dub": xim += ["dawb"] print(colours)
Yuav ua li cas thaum thov print(colours)?
['liab', 'dub', 'dawb']
Txhawm rau zam qhov no, nws raug nquahu kom cuam tshuam nrog daim ntawv siv cov hlais, xws li hauv qhov piv txwv hauv qab no:
xim = ["liab"] rau kuv hauv cov xim[:]: yog kuv == "liab": xim += ["dub"] yog kuv == "dub": xim += ["dawb"] print(colours )
Tshwm sim:
['Liab Dub']
Cov npe tau hloov lawm colours, tab sis qhov kev txiav txim no tsis cuam tshuam rau lub voj voog. Cov ntaub ntawv uas yuav tsum tau rov ua dua tseem tsis hloov pauv thaum lub sijhawm ua haujlwm ntawm lub voj.
Sau npe hauv python 3
Enumerate yog qhov ua haujlwm hauv Python. Feem ntau cov pib tshiab, nrog rau qee tus neeg paub txog programmers, tsis paub txog nws lub neej. Nws tso cai rau koj tuaj yeem suav iterations ntawm lub voj. Piv txwv li:
rau suav, tus nqi hauv enumerate(some_list): print(counter, value)
muaj nuj nqi enumerate kuj yuav siv sij hawm ib qho kev sib cav (tus nqi ntawm lub hauv paus chiv keeb, coj los ntawm lub neej ntawd rau 0). Uas ua rau nws txawm ntau npaum li cas.
my_list = ['apple', 'banana', 'cherry', 'peach'] for c, value in enumerate(my_list, 1): print(c, value) # Result: #1 apple #2 banana #3 cherry # 4 peach