璋佽C璇█涓嶈兘鐜╁鎬侊紵

浣犺偗瀹氬惉璇磋繃C++鐨勮櫄鍑芥暟锛屼絾鐢–璇█璁╃埗绫绘寚閽堣皟鐢ㄥ瓙绫绘柟娉曪紝杩欎簨闈犺氨鍚楋紵涓夊勾鍓嶆垜鎺ユ墜涓€涓祵鍏ュ紡椤圭洰鏃朵篃杩欎箞鎬€鐤戣繃鈥斺€旂洿鍒扮湅瑙佸悓浜嬬敤缁撴瀯浣撳疄鐜颁簡娓告垙瑙掕壊鐨勬妧鑳藉垏鎹紝鎴戞墠鎭嶇劧澶ф偀銆傗€?strong>鈥婥璇█鎼炲姩鎬佺粦瀹氬氨鍍忕敤铻轰笣鍒€鍚冪墰鎺掞紝铏界劧涓嶉『鎵嬩絾纭疄鍙鈥?/strong>鈥嬨€?/p>

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c澶嶅埗
if (shape_type == CIRCLE) calc_circle();
else if (shape_type == SQUARE) calc_square();

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c澶嶅埗
typedef struct {
    double (*calculate)(void* self);  // 馃摝鍏抽敭鍖呰９
    int type;
} Shape;

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娴嬭瘯鏁版嵁鍛婅瘔浣犵湡鐩革細

瀹炵幇鏂瑰紡	浠ｇ爜琛屾暟	鎵╁睍鎴愭湰	鎵ц閫熷害
if-else鍒ゆ柇	200琛?/td>	楂?/td>	0.8ns
鈥?strong>鈥嬪姩鎬佺粦瀹氣€?/strong>鈥?/td>	150琛?/td>	浣?/td>	1.2ns

铏界劧鐗虹壊浜嗙撼绉掔骇鐨勬椂闂达紝浣嗘崲鏉ョ殑鏄悗鏈熺淮鎶ょ殑渚垮埄鎬с€傚浜庨暱鏈熻繍琛岀殑绯荤粺锛岃繖涓氦鎹㈢粷瀵瑰垝绠椼€?/p>

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涓夋瀹炵幇瀹夊叏璋冪敤

鍒鐞嗚鍚撳埌锛岃窡鐫€鎴戝仛灏卞浜嗭紒瀹炵幇鍔ㄦ€佺粦瀹氬彧闇€瑕佷笁姝ワ細

1. 鈥?strong>鈥嬬粰鐖剁被瑁呬釜"鏂规硶浠撳簱"鈥?/strong>鈥?/li>

c澶嶅埗
// 鐖剁被缁撴瀯浣?/span>
typedef struct {
    int type;
    void (*draw)(void* obj);  // 馃帹缁樺浘鏂规硶
} Graphic;

1. 鈥?strong>鈥嬪瓙绫绘敞鍐屼笓灞炴妧鑳解€?/strong>鈥?/li>

c澶嶅埗
// 鍦嗗舰瀛愮被
typedef struct {
    Graphic base;  // 馃П蹇呴』鏀惧湪绗竴涓紒
    int radius;
} Circle;

void circle_draw(void* obj) {
    Circle* c = (Circle*)obj;
    printf("鐢讳釜鍗婂緞%d鐨勫渾", c->radius);
}

1. 鈥?strong>鈥嬭Е鍙戣皟鐢ㄧ殑姝ｇ‘濮垮娍鈥?/strong>鈥?/li>

c澶嶅埗
Graphic* g = (Graphic*)malloc(sizeof(Circle));
g->draw = circle_draw;  // 馃敆缁戝畾鍑芥暟

// 璋冪敤鏃惰寰椾紶鑷韩鍦板潃
g->draw(g);  // 鉁呮纭啓娉?/span>
g->draw();   // 鉂屼細寮曞彂娈甸敊璇?/span>

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鍐呭瓨甯冨眬鐨勯殣钘忛櫡闃?/h3>

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c澶嶅埗
typedef struct {
    int width;     // 馃挜鍗遍櫓鎿嶄綔锛?/span>
    Graphic base;  
} Rectangle;

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楠岃瘉鏂规硶寰堢畝鍗曪細鎵撳嵃缁撴瀯浣撳湴鍧€

c澶嶅埗
printf("瀛愮被鍦板潃:%p\n", (void*)rect);
printf("鐖剁被鍦板潃:%p\n", (void*)&rect->base);  // 鉁呭簲璇ョ浉鍚?/span>

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鎬ц兘浼樺寲鐨勯噹璺瓙

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1. 鈥?strong>鈥嬪嚱鏁版寚閽堥泦涓鐞嗏€?/strong>鈥?/li>

c澶嶅埗
// 鍏ㄥ眬鍞竴铏氳〃
typedef struct {
    void (*draw)(void*);
    void (*move)(void*);
} VirtualTable;

VirtualTable circle_vt = {circle_draw, circle_move};

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1. 鈥?strong>鈥嬬敤瀹忕敓鎴愯浆鎹唬鐮佲€?/strong>鈥?/li>

c澶嶅埗
#define CAST_TO_SUB(type, obj) ((type*)(obj))

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