é¢è¯é¢
1ãPythonæ¯å¦ä½è¿è¡å
å管ççï¼
Pythonçå
å管ç主è¦æä¸ç§æºå¶ï¼å¼ç¨è®¡æ°æºå¶ãåå¾åæ¶æºå¶åå
åæ± æºå¶ã
a. å¼ç¨è®¡æ°
å½ç»ä¸ä¸ªå¯¹è±¡åé
ä¸ä¸ªæ°å称æè
å°ä¸ä¸ªå¯¹è±¡æ¾å
¥ä¸ä¸ªå®¹å¨ï¼å表ãå
ç»æåå
¸ï¼æ¶ï¼è¯¥å¯¹è±¡çå¼ç¨è®¡æ°é½ä¼å¢å ã
å½ä½¿ç¨del对对象æ¾ç¤ºéæ¯æè
å¼ç¨è¶
åºä½ç¨äºæè
被éæ°èµå¼æ¶ï¼è¯¥å¯¹è±¡çå¼ç¨è®¡æ°å°±ä¼åå°ã
å¯ä»¥ä½¿ç¨sys.getrefcount()å½æ°æ¥è·å对象çå½åå¼ç¨è®¡æ°ãå¤æ°æ
åµä¸ï¼å¼ç¨è®¡æ°è¦æ¯æ们çæµç大ç å¤ã对äºä¸å¯åæ°æ®ï¼æ°ååå符串ï¼ï¼è§£éå¨ä¼å¨ç¨åºçä¸åé¨åå
±äº«å
åï¼ä»¥ä¾¿è约å
åã
b. åå¾åæ¶
å½ä¸ä¸ªå¯¹è±¡çå¼ç¨è®¡æ°å½é¶æ¶ï¼å®å°è¢«åå¾æ¶éæºå¶å¤çæã
å½
两个对象aåbç¸äºå¼ç¨æ¶ï¼delè¯å¥å¯ä»¥åå°aåbçå¼ç¨è®¡æ°ï¼å¹¶éæ¯ç¨äºå¼ç¨åºå±å¯¹è±¡çå称ãç¶èç±äºæ¯ä¸ªå¯¹è±¡é½å
å«ä¸ä¸ªå¯¹å
¶ä»å¯¹è±¡çåºç¨ï¼å æ¤å¼ç¨
计æ°ä¸ä¼å½é¶ï¼å¯¹è±¡ä¹ä¸ä¼éæ¯ãï¼ä»è导è´å
åæ³é²ï¼ã为解å³è¿ä¸é®é¢ï¼è§£éå¨ä¼å®ææ§è¡ä¸ä¸ªå¾ªç¯æ£æµå¨ï¼æç´¢ä¸å¯è®¿é®å¯¹è±¡ç循ç¯å¹¶å é¤å®ä»¬ã
c. å
åæ± æºå¶
Pythonæä¾äºå¯¹å
åçåå¾æ¶éæºå¶ï¼ä½æ¯å®å°ä¸ç¨çå
åæ¾å°å
åæ± èä¸æ¯è¿åç»æä½ç³»ç»ã
1ï¼Pymallocæºå¶ã为äºå éPythonçæ§è¡æçï¼Pythonå¼å
¥äºä¸ä¸ªå
åæ± æºå¶ï¼ç¨äºç®¡ç对å°åå
åçç³è¯·åéæ¾ã
2ï¼Pythonä¸ææå°äº256个åèç对象é½ä½¿ç¨pymallocå®ç°çåé
å¨ï¼è大ç对象å使ç¨ç³»ç»ç mallocã
3ï¼å¯¹äºPython对象ï¼å¦æ´æ°ï¼æµ®ç¹æ°åListï¼é½æå
¶ç¬ç«çç§æå
åæ± ï¼å¯¹è±¡é´ä¸å
±äº«ä»ä»¬çå
åæ± ãä¹å°±æ¯è¯´å¦æä½ åé
åéæ¾äºå¤§éçæ´æ°ï¼ç¨äºç¼åè¿äºæ´æ°çå
åå°±ä¸è½ååé
ç»æµ®ç¹æ°ã
ãPythonç¯å¢ã12é Pythoné¢è¯é¢æ»ç»
2ãä»ä¹æ¯lambdaå½æ°ï¼å®æä»ä¹å¥½å¤ï¼
lambda 表达å¼ï¼é常æ¯å¨éè¦ä¸ä¸ªå½æ°ï¼ä½æ¯åä¸æ³è´¹ç¥å»å½åä¸ä¸ªå½æ°çåºåä¸ä½¿ç¨ï¼ä¹å°±æ¯æå¿åå½æ°
lambdaå½æ°ï¼é¦è¦ç¨éæ¯æç¹çå°çåè°å½æ°
lambda [arguments]ï¼ expression
>>> a=lambda xï¼yï¼x+y
>>> a(3ï¼11)
3ãPythonéé¢å¦ä½å®ç°tupleålistç转æ¢ï¼
ç´æ¥ä½¿ç¨tupleålistå½æ°å°±è¡äºï¼type()å¯ä»¥å¤æ对象çç±»åã
4ã请ååºä¸æ®µPython代ç å®ç°å é¤ä¸ä¸ªlistéé¢çéå¤å
ç´ ã
è¿ä¸ªå°æ¹ç¨setå¯ä»¥å®ç°ã
5ãPythonéé¢å¦ä½æ·è´ä¸ä¸ªå¯¹è±¡ï¼ï¼èµå¼ï¼æµ
æ·è´ï¼æ·±æ·è´çåºå«ï¼
èµå¼ï¼=ï¼ï¼å°±æ¯å建äºå¯¹è±¡çä¸ä¸ªæ°çå¼ç¨ï¼ä¿®æ¹å
¶ä¸ä»»æä¸ä¸ªåéé½ä¼å½±åå°å¦ä¸ä¸ªã
æµ
æ·è´ï¼å建ä¸ä¸ªæ°ç对象ï¼ä½å®å
å«çæ¯å¯¹åå§å¯¹è±¡ä¸å
å«é¡¹çå¼ç¨ï¼å¦æç¨å¼ç¨çæ¹å¼ä¿®æ¹å
¶ä¸ä¸ä¸ªå¯¹è±¡ï¼å¦å¤ä¸ä¸ªä¹ä¼ä¿®æ¹æ¹åï¼{1ï¼å®å
¨åçæ¹æ³ï¼2ï¼å·¥åå½æ°ï¼å¦list()ï¼3ï¼copy模åçcopy()å½æ°}
æ·±æ·è´ï¼å建ä¸ä¸ªæ°ç对象ï¼å¹¶ä¸éå½çå¤å¶å®æå
å«ç对象ï¼ä¿®æ¹å
¶ä¸ä¸ä¸ªï¼å¦å¤ä¸ä¸ªä¸ä¼æ¹åï¼{copy模åçdeep.deepcopy()å½æ°}
6ãä»ç»ä¸ä¸exceptçç¨æ³åä½ç¨ï¼
tryâ¦exceptâ¦exceptâ¦[elseâ¦][finallyâ¦]
æ§è¡tryä¸çè¯å¥ï¼å¦æå¼åå¼å¸¸ï¼åæ§è¡è¿ç¨ä¼è·³å°exceptè¯å¥ã对æ¯ä¸ªexceptåæ¯é¡ºåºå°è¯æ§è¡ï¼å¦æå¼åçå¼å¸¸ä¸exceptä¸çå¼å¸¸ç»å¹é
ï¼æ§è¡ç¸åºçè¯å¥ãå¦æææçexcepté½ä¸å¹é
ï¼åå¼å¸¸ä¼ä¼ éå°ä¸ä¸ä¸ªè°ç¨æ¬ä»£ç çæé«å±try代ç ä¸ã
tryä¸çè¯å¥æ£å¸¸æ§è¡ï¼åæ§è¡elseå代ç ãå¦æåçå¼å¸¸ï¼å°±ä¸ä¼æ§è¡
å¦æåå¨finallyè¯å¥ï¼æåæ»æ¯ä¼æ§è¡ã
ãPythonç¯å¢ã12é Pythoné¢è¯é¢æ»ç»
7ãPythonéé¢match()åsearch()çåºå«ï¼
re模åä¸match(patternï¼string [ï¼flags])ï¼æ£æ¥stringçå¼å¤´æ¯å¦ä¸patternå¹é
ã
re模åä¸research(patternï¼string [ï¼flags])ï¼å¨stringæç´¢patternç第ä¸ä¸ªå¹é
å¼ã
>>> print(re.match(âsuperâï¼ âsuperstitionâ).span())
(0ï¼ 5)
>>> print(re.match(âsuperâï¼ âinsuperableâ))
None
>>> print(re.search(âsuperâï¼ âsuperstitionâ).span())
(0ï¼ 5)
>>> print(re.search(âsuperâï¼ âinsuperableâ).span())
(2ï¼ 7)
8ãç¨Pythonå¹é
HTML tagçæ¶åï¼<.*>å<.*ï¼>æä»ä¹åºå«ï¼
æ¯è¯å«è´ªå©ªå¹é
( <.*> )åé贪婪å¹é
( <.*ï¼> )
ä¾å¦ï¼
test
<.*> ï¼
test
<.*ï¼> ï¼
9ã以ä¸ç代ç çè¾åºå°æ¯ä»ä¹ï¼ 说åºä½ ççæ¡å¹¶è§£é
è¾åºï¼
ä½¿ä½ å°æææ¯æå¥çæ¯å
³äºæåä¸è¡çè¾åºæ¯ 3 2 3 èä¸æ¯ 3 2 1ã为ä»ä¹æ¹åäº Parent.x çå¼è¿ä¼æ¹å Child2.x çå¼ï¼ä½æ¯åæ¶ Child1.x å¼å´æ²¡ææ¹åï¼
è¿
个çæ¡çå
³é®æ¯ï¼å¨ Python
ä¸ï¼ç±»åéå¨å
é¨æ¯ä½ä¸ºåå
¸å¤ççãå¦æä¸ä¸ªåéçåå没æå¨å½åç±»çåå
¸ä¸åç°ï¼å°æç´¢ç¥å
ç±»ï¼æ¯å¦ç¶ç±»ï¼ç´å°è¢«å¼ç¨çåéå被æ¾å°ï¼å¦æè¿ä¸ªè¢«å¼ç¨ç
åéåæ¢æ²¡æå¨èªå·±æå¨çç±»å没æå¨ç¥å
ç±»ä¸æ¾å°ï¼ä¼å¼åä¸ä¸ª AttributeError å¼å¸¸ ï¼ã
å æ¤ï¼å¨ç¶ç±»ä¸è®¾ç½® x = 1 ä¼ä½¿å¾ç±»åé X å¨å¼ç¨è¯¥ç±»åå
¶ä»»ä½åç±»ä¸çå¼ä¸º 1ãè¿å°±æ¯å 为第ä¸ä¸ª print è¯å¥çè¾åºæ¯ 1 1 1ã
éåï¼å¦æä»»ä½å®çåç±»éåäºè¯¥å¼ï¼ä¾å¦ï¼æ们æ§è¡è¯å¥ Child1.x = 2ï¼ï¼ç¶åï¼è¯¥å¼ä»
ä»
å¨åç±»ä¸è¢«æ¹åãè¿å°±æ¯ä¸ºä»ä¹ç¬¬äºä¸ª print è¯å¥çè¾åºæ¯ 1 2 1ã
æåï¼å¦æ该å¼å¨ç¶ç±»ä¸è¢«æ¹åï¼ä¾å¦ï¼æ们æ§è¡è¯å¥ Parent.x = 3ï¼ï¼è¿ä¸ªæ¹åä¼å½±åå°ä»»ä½æªéå该å¼çåç±»å½ä¸çå¼ï¼å¨è¿ä¸ªç¤ºä¾ä¸è¢«å½±åçåç±»æ¯ Child2ï¼ãè¿å°±æ¯ä¸ºä»ä¹ç¬¬ä¸ä¸ª print è¾åºæ¯ 3 2 3ã
10ã以ä¸ä»£ç å°è¾åºä»ä¹ï¼
çæ¡
以ä¸ä»£ç å°è¾åº []ï¼å¹¶ä¸ä¸ä¼å¯¼è´ä¸ä¸ª IndexErrorã
æ£å¦äººä»¬æææçï¼è¯å¾è®¿é®ä¸ä¸ªè¶
è¿å表索å¼å¼çæåå°å¯¼è´ IndexErrorï¼æ¯å¦è®¿é®ä»¥ä¸å表ç list[10]ï¼ã尽管å¦æ¤ï¼è¯å¾è®¿é®ä¸ä¸ªå表ç以è¶
åºå表æåæ°ä½ä¸ºå¼å§ç´¢å¼çåçå°ä¸ä¼å¯¼è´ IndexErrorï¼å¹¶ä¸å°ä»
ä»
è¿åä¸ä¸ªç©ºå表ã
ãPythonç¯å¢ã12é Pythoné¢è¯é¢æ»ç»
ä¸ä¸ªè®¨åçå°é®é¢æ¯å®ä¼å¯¼è´åºç° bug ï¼å¹¶ä¸è¿ä¸ªé®é¢æ¯é¾ä»¥è¿½è¸ªçï¼å 为å®å¨è¿è¡æ¶ä¸ä¼å¼åé误ã
11ã以ä¸ç代ç çè¾åºå°æ¯ä»ä¹ï¼ 说åºä½ ççæ¡å¹¶è§£éï¼
ä½ å°å¦ä½ä¿®æ¹ extendList çå®ä¹æ¥äº§çææçç»æ
以ä¸ä»£ç çè¾åºä¸ºï¼
许å¤äººä¼é误ç认为 list1 åºè¯¥çäº [10] 以å list3 åºè¯¥çäº ['a']ã认为 list çåæ°ä¼å¨ extendList æ¯æ¬¡è¢«è°ç¨çæ¶åä¼è¢«è®¾ç½®æå®çé»è®¤å¼ []ã
尽管å¦æ¤ï¼å®é
åççäºæ
æ¯ï¼æ°çé»è®¤å表ä»
ä»
åªå¨å½æ°è¢«å®ä¹æ¶å建ä¸æ¬¡ãéåå½ extendList 没æ被æå®çå表åæ°è°ç¨çæ¶åï¼å
¶ä½¿ç¨çæ¯åä¸ä¸ªå表ãè¿å°±æ¯ä¸ºä»ä¹å½å½æ°è¢«å®ä¹çæ¶åï¼è¡¨è¾¾å¼æ¯ç¨é»è®¤åæ°è¢«è®¡ç®ï¼èä¸æ¯å®è¢«è°ç¨çæ¶åã
å æ¤ï¼list1 å list3 æ¯æä½çç¸åçå表ãè ````list2æ¯æä½çå®å建çç¬ç«çå表ï¼éè¿ä¼ éå®èªå·±ç空å表ä½ä¸ºlist``` åæ°çå¼ï¼ã
extendList å½æ°çå®ä¹å¯ä»¥åå¦ä¸ä¿®æ¹ï¼ä½ï¼å½æ²¡ææ°ç list åæ°è¢«æå®çæ¶åï¼ä¼æ»æ¯å¼å§ä¸ä¸ªæ°å表ï¼è¿æ´å å¯è½æ¯ä¸ç´ææçè¡ä¸ºã
12ã以ä¸ç¨åºè¾åºä»ä¹ï¼
好
å§ï¼ç¬¬ä¸è¡ä»£ç è§å¯¹æ¯æ第ä¸æ¬¡è§ï¼ç¬¬ä¸è¡è¾åºçæ¯[[]ï¼ []ï¼ []ï¼ []ï¼ []]ï¼ä¸ä¸ªå«æ5个空å表çå表ï¼è第äºè¡è¾åºçæ¯[[10]ï¼
[10]ï¼ [10]ï¼ [10]ï¼
[10]]ï¼æåªè½è§£é为è¿5个å表æåäºåä¸ä¸ªå表ï¼æ以修æ¹ä»»æä¸ä¸ªå
¶å®4个é½ä¼æ¹åï¼å¯ä»¥ç¨list[0]=10 æå¼ä¸ä¸ªè¿æ¥è¯è¯ã
温馨提示:答案为网友推荐,仅供参考