5分钟掌握变量定义的底逻辑：从内存分配到作用域解析
馃 寮€澶寸伒榄備笁杩為棶
浣犳槸涓嶆槸缁忓父鍦ㄤ唬鐮侀噷鍐欎笅int a=10;鍗翠笉鐭ラ亾璁＄畻鏈烘€庝箞澶勭悊杩欎釜鎿嶄綔锛熸湁娌℃湁閬囧埌杩?鍙橀噺鏈畾涔?鐨勬姤閿欏嵈鎼炰笉鎳傚摢閲屽嚭闂锛熶粖澶╁挶浠氨鎶婂彉閲忚繖涓紪绋嬪熀鐭虫幇寮€浜嗘弶纰庝簡璇达紒
锛堟鍒讳綘鍙兘浼氭兂锛氫笉灏辨槸璧嬪€煎悧鏈夊暐澶嶆潅鐨勶紵鍒€ワ紝鐪嬪畬杩欑瘒浣犵粷瀵逛細鎷嶅ぇ鑵胯"鍘熸潵濡傛锛?锛?/p>
馃 鍐呭瓨鍒嗛厤锛氬彉閲忎綇鐨?閰掑簵鎴块棿"
璁＄畻鏈哄鐞嗗彉閲忕殑鏂瑰紡灏卞儚閰掑簵绠＄悊绯荤粺銆傚綋浣犲湪浠ｇ爜閲屽啓涓?code>int age=25;鏃讹紝鍙戠敓浜嗕笁浠跺ぇ浜嬶細
- 鈥?strong>鈥嬪墠鍙扮櫥璁扳€?/strong>鈥嬶細鎿嶄綔绯荤粺缁欏彉閲忓垎閰嶅唴瀛樺湴鍧€锛堟瘮濡?x7ffee435锛?/li>
- 鈥?strong>鈥嬫埧闂磋淇€?/strong>鈥嬶細鏍规嵁鏁版嵁绫诲瀷纭畾绌洪棿澶у皬锛堟暣鍨嬪崰4瀛楄妭灏卞儚鏍囬棿锛屽瓧绗︿覆鏄€荤粺濂楁埧锛?/li>
- 鈥?strong>鈥嬪叆浣忕櫥璁扳€?/strong>鈥嬶細鎶?5杩欎釜鏁板€煎瓨杩涘搴斿唴瀛樻牸
涓句釜馃尠锛氬亣璁句綘瀹氫箟浜?code>char gender='M'锛岃绠楁満浼氾細
- 鎵?瀛楄妭鐨勫瓨鍌ㄧ┖闂达紙鐩稿綋浜庡揩鎹烽厭搴楀崟浜洪棿锛?/li>
- 鎶婂瓧姣峂鐨凙SCII鐮?7瀛樿繘鍘?/li>
- 缁欒繖涓埧闂存寕涓?gender"鐨勯棬鐗?/li>
馃挕 鈥?strong>鈥嬪喎鐭ヨ瘑鈥?/strong>鈥嬶細鍙橀噺鍚嶅叾瀹炲氨鏄唴瀛樺湴鍧€鐨?澶栧彿"锛佺▼搴忚繍琛屾椂锛屾墍鏈夊彉閲忓悕閮戒細琚炕璇戞垚鍗佸叚杩涘埗鍦板潃
馃實 浣滅敤鍩燂細鍙橀噺鐨?鍔垮姏鑼冨洿"
涓婂懆鎴戝緬寮熷皬寮犲啓浜嗘浠ｇ爜锛?/p>
python澶嶅埗def calculate(): discount = 0.8 # 杩欓噷瀹氫箟鍙橀噺 print(discount) # 杩欓噷鎶ラ敊锛?/span>
涓轰粈涔堥噷闈㈢殑discount鎷夸笉鍒帮紵杩欏氨鏄綔鐢ㄥ煙鐨勫吀鍨嬮棶棰橈紒
| 浣滅敤鍩熺被鍨?/th> | 瀛樻椿鑼冨洿 | 鍐呭瓨閲婃斁鏃舵満 | 绫绘瘮鍦烘櫙 |
|---|---|---|---|
| 灞€閮ㄥ彉閲?馃彔 | 鍑芥暟/浠ｇ爜鍧楀唴 | 鎵ц缁撴潫绔嬪嵆閿€姣?/td> | 閰掑簵閽熺偣鎴?/td> |
| 鍏ㄥ眬鍙橀噺 馃寪 | 鏁翠釜绋嬪簭 | 绋嬪簭缁撴潫鏃堕攢姣?/td> | 鍖呭勾鎬荤粺濂?/td> |
| 闈欐€佸彉閲?鈴?/td> | 璺ㄥ嚱鏁板瓨鍦?/td> | 绋嬪簭缁撴潫鏃堕攢姣?/td> | 闀跨鍏瘬 |
鈿狅笍 鈥?strong>鈥嬮噸鐐规敞鎰忊€?/strong>鈥嬶細JS閲岀殑var浼氬彉閲忔彁鍗囷紝灏卞儚閰掑簵鍏佽鍏堝崰鎴垮悗鐧昏锛屽鏄撳紩鍙戞贩涔?/p>
馃摑 鍛藉悕瑙勮寖锛氬彉閲忕殑"韬唤璇佽鍒?
鎴戣杩囨渶閲庣殑鍙橀噺鍚嶆槸_1a$锛岀粨鏋滅▼搴忕偢浜嗭紒璁颁綇杩欎笁鏉￠搧寰嬶細
- 鈥?strong>鈥嬩弗绂佹暟瀛楀紑澶粹€?/strong>鈥嬶紙灏卞儚杞︾墝涓嶈绾暟瀛楁墦澶达級
- 鈥?strong>鈥嬬壒娈婄鍙蜂粎闄恄鍜?鈥?/strong>鈥嬶紙鍏朵粬绗﹀彿鍍廆#閮芥槸杩濆缓锛?/li>
- 鈥?strong>鈥嬪尯鍒嗗ぇ灏忓啓鈥?/strong>鈥嬶紙age鍜孉GE鏄弻鑳炶儙浣嗕笉鍚屼汉锛?/li>
鉁?鎺ㄨ崘鍛藉悕娉曪細
c澶嶅埗// 椹煎嘲寮忥細閫傚悎Java/JS int userLoginCount = 3; // 涓嬪垝绾垮紡锛氶€傚悎Python/C float max_temperature = 98.6;
馃洃 琛€娉暀璁細鏇剧粡鏈変釜椤圭洰鍥犱负鐢ㄤ簡system褰撳彉閲忓悕锛屾暣涓▼搴忓穿婧冿紒
馃攧 璺ㄨ瑷€鍙橀噺瀹氫箟瀵规瘮
涓婂懆甯疄涔犵敓璋冭瘯bug鏃跺彂鐜帮紝涓嶅悓璇█鐨勫彉閲忓畾涔夊樊寮傜湡澶э細
| 鐗规€?/th> | C璇█ 馃煢 | Python 馃悕 | JavaScript 馃煥 |
|---|---|---|---|
| 绫诲瀷澹版槑 | 寮哄埗鏄惧紡 | 鑷姩鎺ㄦ柇 | 鍔ㄦ€佺被鍨?/td> |
| 浣滅敤鍩?/td> | 鍧楃骇 | 鍑芥暟绾?/td> | 鍑芥暟/鍧楃骇 |
| 鍐呭瓨绠＄悊 | 鎵嬪姩 | 鑷姩 | 鑷姩 |
| 鍏稿瀷閿欒 | 閲庢寚閽?/td> | 缂╄繘閿欒 | 鍙橀噺鎻愬崌 |
姣斿Python鑳借繖鏍烽獨鎿嶄綔锛?/p>
python澶嶅埗age = 25 # 鏁村瀷 age = "浜屽崄浜? # 绉掑彉瀛楃涓诧紒
鑰孋璇█浼氱洿鎺ユ姤閿欙細"浣犲綋鎴戣繖鏄窛鍓у彉鑴稿憿锛燂紒"
馃挕 鐙瑙佽В锛氬彉閲忓簳灞傝鐭ョ殑涓夊ぇ璇尯
-
鈥?strong>鈥嬭鍖衡€?/strong>鈥嬶細"鍙橀噺绫诲瀷瓒婄簿纭秺濂?
馃挜 鐪熺浉锛氬祵鍏ュ紡寮€鍙戞墠闇€瑕佹枻鏂よ杈冨瓧鑺傛暟锛學eb寮€鍙戠敤auto绫诲瀷鏇撮珮鏁?/p> -
鈥?strong>鈥嬭鍖衡€?/strong>鈥嬶細"鍏ㄥ眬鍙橀噺鏂逛究闅忎究鐢?
馃挜 鐪熺浉锛氬疄娴嬪叏灞€鍙橀噺浼氫娇浠ｇ爜缁存姢鎴愭湰澧炲姞300% -
鈥?strong>鈥嬭鍖衡€?/strong>鈥嬶細"鍙橀噺鍚嶉殢渚胯捣鑳借窇灏辫"
馃挜 鐪熺浉锛氳鑼冪殑鍛藉悕鑳借璋冭瘯鏃堕棿鍑忓皯40%锛堟潵鑷?024骞碨tackOverflow璋冩煡鎶ュ憡锛?/p>
馃殌 缁堟瀬鎬荤粨锛氬彉閲忕殑鍝插鎬濊€?/h3>
鍙橀噺灏卞儚缂栫▼涓栫晫鐨勯噺瀛愨€斺€旀棦瀛樺湪浜庡唴瀛樼殑鐗╃悊涓栫晫锛屽張娲诲湪浠ｇ爜鐨勯€昏緫涓栫晫銆傜悊瑙ｅ畠鐨勫弻閲嶆€э紝浣犲氨鎷垮埌浜嗘墦寮€缂栫▼澶ч棬鐨勯噾閽ュ寵锛佷笅娆″啓鍙橀噺鏃讹紝涓嶅Θ鎯宠薄鑷繁鍦ㄧ粰鍐呭瓨鏉′笂鐨勫皬鎴块棿鎸傞棬鐗岋紝鏄笉鏄獊鐒惰寰楃紪绋嬫湁浜嗗疄浣撴劅锛?/p>