\u7c7b(class)\u662f\u4e00\u79cd\u5c06\u6570\u636e\u548c\u51fd\u6570\u7ec4\u7ec7\u5728\u540c\u4e00\u4e2a\u7ed3\u6784\u91cc\u7684\u903b\u8f91\u65b9\u6cd5\u3002\u5b9a\u4e49\u7c7b\u7684\u5173\u952e\u5b57\u4e3aclass \uff0c\u5176\u529f\u80fd\u4e0eC\u8bed\u8a00\u4e2d\u7684struct\u7c7b\u4f3c\uff0c\u4e0d\u540c\u4e4b\u5904\u662fclass\u53ef\u4ee5\u5305\u542b\u51fd\u6570\uff0c\u800c\u4e0d\u50cfstruct\u53ea\u80fd\u5305\u542b\u6570\u636e\u5143\u7d20\u3002<\/p>\n\n\n\n
\u7c7b\u5b9a\u4e49\u7684\u5f62\u5f0f\u662f\uff1a<\/p>\n\n\n\n
class class_name {
permission_label_1:
member1;
permission_label_2:
member2;
...
} object_name;
<\/pre>\n\n\n\n\u5176\u4e2d class_name \u662f\u7c7b\u7684\u540d\u79f0 (\u7528\u6237\u81ea\u5b9a\u4e49\u7684\u7c7b\u578b) \uff0c\u800c\u53ef\u9009\u9879object_name \u662f\u4e00\u4e2a\u6216\u51e0\u4e2a\u5bf9\u8c61(object)\u6807\u8bc6\u3002Class\u7684\u58f0\u660e\u4f53\u4e2d\u5305\u542b\u6210\u5458members\uff0c\u6210\u5458\u53ef\u4ee5\u662f\u6570\u636e\u6216\u51fd\u6570\u5b9a\u4e49\uff0c\u540c\u65f6\u4e5f\u53ef\u4ee5\u5305\u62ec\u5141\u8bb8\u8303\u56f4\u6807\u5fd7 permission labels\uff0c\u8303\u56f4\u6807\u5fd7\u53ef\u4ee5\u662f\u4ee5\u4e0b\u4e09\u4e2a\u5173\u952e\u5b57\u4e2d\u4efb\u610f\u4e00\u4e2a\uff1aprivate:, public: \u6216 protected:\u3002\u5b83\u4eec\u5206\u522b\u4ee3\u8868\u4ee5\u4e0b\u542b\u4e49\uff1a<\/p>\n\n\n\n
\u5982\u679c\u6211\u4eec\u5728\u5b9a\u4e49\u4e00\u4e2aclass\u6210\u5458\u7684\u65f6\u5019\u6ca1\u6709\u58f0\u660e\u5176\u5141\u8bb8\u8303\u56f4\uff0c\u8fd9\u4e9b\u6210\u5458\u5c06\u88ab\u9ed8\u8ba4\u4e3a private\u8303\u56f4\u3002<\/p>\n\n\n\n
\u4f8b\u5982\uff1a 4.1 \u7c7b\uff08Classes\uff09 \u7c7b(class)\u662f\u4e00\u79cd\u5c06\u6570\u636e\u548c\u51fd\u6570\u7ec4\u7ec7\u5728\u540c\u4e00\u4e2a\u7ed3\u6784\u91cc\u7684\u903b\u8f91\u65b9\u6cd5\u3002\u5b9a\u4e49\u7c7b\u7684\u5173\u952e\u5b57\u4e3aclass \uff0c\u5176\u529f\u80fd\u4e0eC\u8bed\u8a00\u4e2d\u7684struct\u7c7b\u4f3c\uff0c\u4e0d\u540c\u4e4b\u5904\u662fclass\u53ef\u4ee5\u5305\u542b\u51fd\u6570\uff0c\u800c\u4e0d\u50cfstruct\u53ea\u80fd\u5305\u542b\u6570\u636e\u5143\u7d20\u3002 \u7c7b\u5b9a\u4e49\u7684\u5f62\u5f0f\u662f\uff1a class class_name { permission_label_1: member1; permission_label_2: member2; … } object_name; \u5176\u4e2d class_name \u662f\u7c7b\u7684\u540d\u79f0 (\u7528\u6237\u81ea\u5b9a\u4e49\u7684\u7c7b\u578b) \uff0c\u800c\u53ef\u9009\u9879object_name \u662f\u4e00\u4e2a\u6216\u51e0\u4e2a\u5bf9\u8c61(object)\u6807\u8bc6\u3002Class\u7684\u58f0\u660e\u4f53\u4e2d\u5305\u542b\u6210\u5458members\uff0c\u6210\u5458\u53ef\u4ee5\u662f\u6570\u636e\u6216\u51fd\u6570\u5b9a\u4e49\uff0c\u540c\u65f6\u4e5f\u53ef\u4ee5\u5305\u62ec\u5141\u8bb8\u8303\u56f4\u6807\u5fd7 permission labels\uff0c\u8303\u56f4\u6807\u5fd7\u53ef\u4ee5\u662f\u4ee5\u4e0b\u4e09\u4e2a\u5173\u952e\u5b57\u4e2d\u4efb\u610f\u4e00\u4e2a\uff1aprivate:, public: \u6216 protected:\u3002\u5b83\u4eec\u5206\u522b\u4ee3\u8868\u4ee5\u4e0b\u542b\u4e49\uff1a private \uff1aclass\u7684private\u6210\u5458\uff0c\u53ea\u6709\u540c\u4e00\u4e2aclass\u7684\u5176\u4ed6\u6210\u5458\u6216\u8be5class\u7684\u201cfriend\u201d class\u53ef\u4ee5\u8bbf\u95ee\u8fd9\u4e9b\u6210\u5458\u3002 protected \uff1aclass\u7684protected\u6210\u5458\uff0c\u53ea\u6709\u540c\u4e00\u4e2aclass\u7684\u5176\u4ed6\u6210\u5458\uff0c\u6216\u8be5class\u7684\u201cfriend\u201d class\uff0c\u6216\u8be5class\u7684\u5b50\u7c7b(derived classes) \u53ef\u4ee5\u8bbf\u95ee\u8fd9\u4e9b\u6210\u5458\u3002 public \uff1aclass\u7684public\u6210\u5458\uff0c\u4efb\u4f55\u53ef\u4ee5\u770b\u5230\u8fd9\u4e2aclass\u7684\u5730\u65b9\u90fd\u53ef\u4ee5\u8bbf\u95ee\u8fd9\u4e9b\u6210\u5458\u3002 \u5982\u679c\u6211\u4eec\u5728\u5b9a\u4e49\u4e00\u4e2aclass\u6210\u5458\u7684\u65f6\u5019\u6ca1\u6709\u58f0\u660e\u5176\u5141\u8bb8\u8303\u56f4\uff0c\u8fd9\u4e9b\u6210\u5458\u5c06\u88ab\u9ed8\u8ba4\u4e3a private\u8303\u56f4\u3002 \u4f8b\u5982\uff1a class CRectangle { int x, y;public:void set_values (int,int);int area (void);} rect;\u4e0a\u9762\u4f8b\u5b50\u5b9a\u4e49\u4e86\u4e00\u4e2aclass CRectangle \u548c\u8be5class\u7c7b\u578b\u7684\u5bf9\u8c61\u53d8\u91cfrect \u3002\u8fd9\u4e2aclass \u67094\u4e2a\u6210\u5458\uff1a\u4e24\u4e2a\u6574\u578b\u53d8\u91cf (x […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":351,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"_links":{"self":[{"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/pages\/353"}],"collection":[{"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/comments?post=353"}],"version-history":[{"count":1,"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/pages\/353\/revisions"}],"predecessor-version":[{"id":354,"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/pages\/353\/revisions\/354"}],"up":[{"embeddable":true,"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/pages\/351"}],"wp:attachment":[{"href":"https:\/\/www.prglab.com\/blog\/wp-json\/wp\/v2\/media?parent=353"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} class CRectangle {
int x, y;
public:
void set_values (int,int);
int area (void);
} rect;
\u4e0a\u9762\u4f8b\u5b50\u5b9a\u4e49\u4e86\u4e00\u4e2aclass CRectangle \u548c\u8be5class\u7c7b\u578b\u7684\u5bf9\u8c61\u53d8\u91cfrect \u3002\u8fd9\u4e2aclass \u67094\u4e2a\u6210\u5458\uff1a\u4e24\u4e2a\u6574\u578b\u53d8\u91cf (x \u548c y) \uff0c\u5728private \u90e8\u5206 (\u56e0\u4e3aprivate \u662f\u9ed8\u8ba4\u7684\u5141\u8bb8\u8303\u56f4)\uff1b\u4ee5\u53ca\u4e24\u4e2a\u51fd\u6570\uff0c \u5728 public \u90e8\u5206\uff1aset_values() \u548c area()\uff0c\u8fd9\u91cc\u53ea\u5305\u542b\u4e86\u51fd\u6570\u7684\u539f\u578b(prototype)\u3002\u6ce8\u610f<\/strong>class\u540d\u79f0\u4e0e\u5bf9\u8c61(object)\u540d\u79f0\u7684\u4e0d\u540c\uff1a\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0cCRectangle \u662fclass \u540d\u79f0 (\u5373\u7528\u6237\u5b9a\u4e49\u7684\u7c7b\u578b\u540d\u79f0)\uff0c\u800crect \u662f\u4e00\u4e2aCRectangle\u7c7b\u578b\u7684\u5bf9\u8c61\u540d\u79f0\u3002\u5b83\u4eec\u7684\u533a\u522b\u5c31\u50cf\u4e0b\u9762\u4f8b\u5b50\u4e2d\u7c7b\u578b\u540d int\u548c \u53d8\u91cf\u540da \u7684\u533a\u522b\u4e00\u6837\uff1aint a;int \u662fclass\u540d\u79f0 (\u7c7b\u578b\u540d) \uff0c\u800ca \u662f\u5bf9\u8c61\u540d object name (\u53d8\u91cf)\u3002\u5728\u7a0b\u5e8f\u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528\u5bf9\u8c61\u540d\u540e\u9762\u52a0\u4e00\u70b9\u518d\u52a0\u6210\u5458\u540d\u79f0\uff08\u540c\u4f7f\u7528C structs\u4e00\u6837\uff09\uff0c\u6765\u5f15\u7528\u5bf9\u8c61rect \u7684\u4efb\u4f55public\u6210\u5458\uff0c\u5c31\u50cf\u5b83\u4eec\u53ea\u662f\u4e00\u822c\u7684\u51fd\u6570\u6216\u53d8\u91cf\u3002\u4f8b\u5982\uff1arect.set_value (3,4);
myarea = rect.area();\u4f46\u6211\u4eec\u4e0d\u80fd\u591f\u5f15\u7528 x \u6216 y \uff0c\u56e0\u4e3a\u5b83\u4eec\u662f\u8be5class\u7684 private \u6210\u5458\uff0c\u5b83\u4eec\u53ea\u80fd\u591f\u5728\u8be5class\u7684\u5176\u5b83\u6210\u5458\u4e2d\u88ab\u5f15\u7528\u3002\u6655\u4e86\u5417\uff1f\u4e0b\u9762\u662f\u5173\u4e8eclass CRectangle\u7684\u4e00\u4e2a\u590d\u6742\u7684\u4f8b\u5b50\uff1a \/\/ classes example #include <iostream.h> class CRectangle { int x, y; public: void set_values (int,int); int area (void) {return (x*y);} }; void CRectangle::set_values (int a, int b) { x = a; y = b; } int main () { CRectangle rect; rect.set_values (3,4); cout << \"area: \" << rect.area(); } area: 12\u4e0a\u9762\u4ee3\u7801\u4e2d\u65b0\u7684\u4e1c\u897f\u662f\u5728\u5b9a\u4e49\u51fd\u6570set_values().\u4f7f\u7528\u7684\u8303\u56f4\u64cd\u4f5c\u7b26(\u53cc\u5192\u53f7:: )\u3002\u5b83\u662f\u7528\u6765\u5728\u4e00\u4e2aclass\u4e4b\u5916\u5b9a\u4e49\u8be5class\u7684\u6210\u5458\u3002\u6ce8\u610f\uff0c\u6211\u4eec\u5728CRectangle class\u5185\u90e8\u5df2\u7ecf\u5b9a\u4e49\u4e86\u51fd\u6570area() \u7684\u5177\u4f53\u64cd\u4f5c\uff0c\u56e0\u4e3a\u8fd9\u4e2a\u51fd\u6570\u975e\u5e38\u7b80\u5355\u3002\u800c\u5bf9\u51fd\u6570set_values() \uff0c\u5728class\u5185\u90e8\u53ea\u662f\u5b9a\u4e49\u4e86\u5b83\u7684\u539f\u578bprototype\uff0c\u800c\u5176\u5b9e\u73b0\u662f\u5728class\u4e4b\u5916\u5b9a\u4e49\u7684\u3002\u8fd9\u79cd\u5728class\u4e4b\u5916\u5b9a\u4e49\u5176\u6210\u5458\u7684\u60c5\u51b5\u5fc5\u987b\u4f7f\u7528\u8303\u56f4\u64cd\u4f5c\u7b26::\u3002\u8303\u56f4\u64cd\u4f5c\u7b26 (::) \u58f0\u660e\u4e86\u88ab\u5b9a\u4e49\u7684\u6210\u5458\u6240\u5c5e\u7684class\u540d\u79f0\uff0c\u5e76\u8d4b\u4e88\u88ab\u5b9a\u4e49\u6210\u5458\u9002\u5f53\u7684\u8303\u56f4\u5c5e\u6027\uff0c\u8fd9\u4e9b\u8303\u56f4\u5c5e\u6027\u4e0e\u5728class\u5185\u90e8\u5b9a\u4e49\u6210\u5458\u7684\u5c5e\u6027\u662f\u4e00\u6837\u7684\u3002\u4f8b\u5982\uff0c\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u5728\u51fd\u6570set_values() \u4e2d\u5f15\u7528\u4e86private\u53d8\u91cfx \u548c y\uff0c\u8fd9\u4e9b\u53d8\u91cf\u53ea\u6709\u5728class\u5185\u90e8\u548c\u5b83\u7684\u6210\u5458\u4e2d\u624d\u662f\u53ef\u89c1\u7684\u3002\u5728class\u5185\u90e8\u76f4\u63a5\u5b9a\u4e49\u5b8c\u6574\u7684\u51fd\u6570\uff0c\u548c\u53ea\u5b9a\u4e49\u51fd\u6570\u7684\u539f\u578b\u800c\u628a\u5177\u4f53\u5b9e\u73b0\u653e\u5728class\u5916\u90e8\u7684\u552f\u4e00\u533a\u522b\u5728\u4e8e\uff0c\u5728\u7b2c\u4e00\u79cd\u60c5\u51b5\u4e2d\uff0c\u7f16\u8bd1\u5668(compiler) \u4f1a\u81ea\u52a8\u5c06\u51fd\u6570\u4f5c\u4e3ainline \u8003\u8651\uff0c\u800c\u5728\u7b2c\u4e8c\u79cd\u60c5\u51b5\u4e0b\uff0c\u51fd\u6570\u53ea\u662f\u4e00\u822c\u7684class\u6210\u5458\u51fd\u6570\u3002\u6211\u4eec\u628a x \u548c y \u5b9a\u4e49\u4e3aprivate \u6210\u5458 (\u8bb0\u4f4f\uff0c\u5982\u679c\u6ca1\u6709\u7279\u6b8a\u58f0\u660e\uff0c\u6240\u6709class\u7684\u6210\u5458\u5747\u9ed8\u8ba4\u4e3aprivate )\uff0c\u539f\u56e0\u662f\u6211\u4eec\u5df2\u7ecf\u5b9a\u4e49\u4e86\u4e00\u4e2a\u8bbe\u7f6e\u8fd9\u4e9b\u53d8\u91cf\u503c\u7684\u51fd\u6570 (set_values()) \uff0c\u8fd9\u6837\u4e00\u6765\uff0c\u5728\u7a0b\u5e8f\u7684\u5176\u5b83\u5730\u65b9\u5c31\u6ca1\u6709\u529e\u6cd5\u76f4\u63a5\u8bbf\u95ee\u5b83\u4eec\u3002\u4e5f\u8bb8\u5728\u4e00\u4e2a\u8fd9\u6837\u7b80\u5355\u7684\u4f8b\u5b50\u4e2d\uff0c\u4f60\u65e0\u6cd5\u770b\u5230\u8fd9\u6837\u4fdd\u62a4\u4e24\u4e2a\u53d8\u91cf\u6709\u4ec0\u4e48\u610f\u4e49\uff0c\u4f46\u5728\u6bd4\u8f83\u590d\u6742\u7684\u7a0b\u5e8f\u4e2d\uff0c\u8fd9\u662f\u975e\u5e38\u91cd\u8981\u7684\uff0c\u56e0\u4e3a\u5b83\u4f7f\u5f97\u53d8\u91cf\u4e0d\u4f1a\u88ab\u610f\u5916\u4fee\u6539 \uff08\u8fd9\u91cc\u610f\u5916\u6307\u7684\u662f\u4eceobject\u7684\u89d2\u5ea6\u6765\u8bb2\u7684\u610f\u5916\uff09\u3002\u4f7f\u7528class\u7684\u4e00\u4e2a\u66f4\u5927\u7684\u597d\u5904\u662f\u6211\u4eec\u53ef\u4ee5\u7528\u5b83\u6765\u5b9a\u4e49\u591a\u4e2a\u4e0d\u540c\u5bf9\u8c61(object)\u3002\u4f8b\u5982\uff0c\u63a5\u7740\u4e0a\u9762class CRectangle\u7684\u4f8b\u5b50\uff0c\u9664\u4e86\u5bf9\u8c61rect\u4e4b\u5916\uff0c\u6211\u4eec\u8fd8\u53ef\u4ee5\u5b9a\u4e49\u5bf9\u8c61rectb \uff1a \/\/ class example #include <iostream.h> class CRectangle { int x, y; public: void set_values (int,int); int area (void) {return (x*y);} }; void CRectangle::set_values (int a, int b) { x = a; y = b; } int main () { CRectangle rect, rectb; rect.set_values (3,4); rectb.set_values (5,6); cout << \"rect area: \" << rect.area() << endl; cout << \"rectb area: \" << rectb.area() << endl; } rect area: 12
rectb area: 30\u6ce8\u610f<\/strong>: \u8c03\u7528\u51fd\u6570rect.area() \u4e0e\u8c03\u7528rectb.area()\u6240\u5f97\u5230\u7684\u7ed3\u679c\u662f\u4e0d\u4e00\u6837\u7684\u3002\u8fd9\u662f\u56e0\u4e3a\u6bcf\u4e00\u4e2aclass CRectangle \u7684\u5bf9\u8c61\u90fd\u62e5\u6709\u5b83\u81ea\u5df1\u7684\u53d8\u91cf x \u548c y\uff0c\u4ee5\u53ca\u5b83\u81ea\u5df1\u7684\u51fd\u6570set_value() \u548c area()\u3002\u8fd9\u662f\u57fa\u4e8e\u5bf9\u8c61( object) \u548c \u9762\u5411\u5bf9\u8c61\u7f16\u7a0b (object-oriented programming)\u7684\u6982\u5ff5\u7684\u3002\u8fd9\u4e2a\u6982\u5ff5\u4e2d\uff0c\u6570\u636e\u548c\u51fd\u6570\u662f\u5bf9\u8c61(object)\u7684\u5c5e\u6027(properties)\uff0c\u800c\u4e0d\u662f\u50cf\u4ee5\u524d\u5728\u7ed3\u6784\u5316\u7f16\u7a0b (structured programming) \u4e2d\u6240\u8ba4\u4e3a\u7684\u5bf9\u8c61(object)\u662f\u51fd\u6570\u53c2\u6570\u3002\u5728\u672c\u8282\u53ca\u540e\u9762\u7684\u5c0f\u8282\u4e2d\uff0c\u6211\u4eec\u5c06\u8ba8\u8bba\u9762\u5411\u5bf9\u8c61\u7f16\u7a0b\u7684\u597d\u5904\u3002\u5728\u8fd9\u4e2a\u5177\u4f53\u7684\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u8ba8\u8bba\u7684class (object\u7684\u7c7b\u578b)\u662fCRectangle\uff0c\u6709\u4e24\u4e2a\u5b9e\u4f8b(instance)\uff0c\u6216\u79f0\u5bf9\u8c61(object)\uff1arect \u548c rectb\uff0c\u6bcf\u4e00\u4e2a\u6709\u5b83\u81ea\u5df1\u7684\u6210\u5458\u53d8\u91cf\u548c\u6210\u5458\u51fd\u6570\u3002
\u6784\u9020\u51fd\u6570\u548c\u6790\u6784\u51fd\u6570 (Constructors and destructors)\u5bf9\u8c61(object)\u5728\u751f\u6210\u8fc7\u7a0b\u4e2d\u901a\u5e38\u9700\u8981\u521d\u59cb\u5316\u53d8\u91cf\u6216\u5206\u914d\u52a8\u6001\u5185\u5b58\uff0c\u4ee5\u4fbf\u6211\u4eec\u80fd\u591f\u64cd\u4f5c\uff0c\u6216\u9632\u6b62\u5728\u6267\u884c\u8fc7\u7a0b\u4e2d\u8fd4\u56de\u610f\u5916\u7ed3\u679c\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u5982\u679c\u6211\u4eec\u5728\u8c03\u7528\u51fd\u6570set_values( ) \u4e4b\u524d\u5c31\u8c03\u7528\u4e86\u51fd\u6570area()\uff0c\u5c06\u4f1a\u4ea7\u751f\u4ec0\u4e48\u6837\u7684\u7ed3\u679c\u5462\uff1f\u53ef\u80fd\u4f1a\u662f\u4e00\u4e2a\u4e0d\u786e\u5b9a\u7684\u503c\uff0c\u56e0\u4e3a\u6210\u5458x \u548c y \u8fd8\u6ca1\u6709\u88ab\u8d4b\u4e8e\u4efb\u4f55\u503c\u3002\u4e3a\u4e86\u907f\u514d\u8fd9\u79cd\u60c5\u51b5\u53d1\u751f\uff0c\u4e00\u4e2aclass \u53ef\u4ee5\u5305\u542b\u4e00\u4e2a\u7279\u6b8a\u7684\u51fd\u6570\uff1a\u6784\u9020\u51fd\u6570 constructor\uff0c\u5b83\u53ef\u4ee5\u901a\u8fc7\u58f0\u660e\u4e00\u4e2a\u4e0eclass\u540c\u540d\u7684\u51fd\u6570\u6765\u5b9a\u4e49\u3002\u5f53\u4e14\u4ec5\u5f53\u8981\u751f\u6210\u4e00\u4e2aclass\u7684\u65b0\u7684\u5b9e\u4f8b (instance)\u7684\u65f6\u5019\uff0c\u4e5f\u5c31\u662f\u5f53\u4e14\u4ec5\u5f53\u58f0\u660e\u4e00\u4e2a\u65b0\u7684\u5bf9\u8c61\uff0c\u6216\u7ed9\u8be5class\u7684\u4e00\u4e2a\u5bf9\u8c61\u5206\u914d\u5185\u5b58\u7684\u65f6\u5019\uff0c\u8fd9\u4e2a\u6784\u9020\u51fd\u6570\u5c06\u81ea\u52a8\u88ab\u8c03\u7528\u3002\u4e0b\u9762\uff0c\u6211\u4eec\u5c06\u5b9e\u73b0\u5305\u542b\u4e00\u4e2a\u6784\u9020\u51fd\u6570\u7684CRectangle \uff1a \/\/ class example #include <iostream.h> class CRectangle { int width, height; public: CRectangle (int,int); int area (void) {return (width*height);} }; CRectangle::CRectangle (int a, int b) { width = a; height = b; } int main () { CRectangle rect (3,4); CRectangle rectb (5,6); cout << \"rect area: \" << rect.area() << endl; cout << \"rectb area: \" << rectb.area() << endl; } rect area: 12
rectb area: 30\u6b63\u5982\u4f60\u6240\u770b\u5230\u7684\uff0c\u8fd9\u4e2a\u4f8b\u5b50\u7684\u8f93\u51fa\u7ed3\u679c\u4e0e\u524d\u9762\u4e00\u4e2a\u6ca1\u6709\u533a\u522b\u3002\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u53ea\u662f\u628a\u51fd\u6570set_values\u6362\u6210\u4e86class\u7684\u6784\u9020\u51fd\u6570constructor\u3002\u6ce8\u610f\u8fd9\u91cc\u53c2\u6570\u662f\u5982\u4f55\u5728class\u5b9e\u4f8b (instance)\u751f\u6210\u7684\u65f6\u5019\u4f20\u9012\u7ed9\u6784\u9020\u51fd\u6570\u7684\uff1aCRectangle rect (3,4);
CRectangle rectb (5,6);\u540c\u65f6\u4f60\u53ef\u4ee5\u770b\u5230\uff0c\u6784\u9020\u51fd\u6570\u7684\u539f\u578b\u548c\u5b9e\u73b0\u4e2d\u90fd\u6ca1\u6709\u8fd4\u56de\u503c(return value)\uff0c\u4e5f\u6ca1\u6709void \u7c7b\u578b\u58f0\u660e\u3002\u6784\u9020\u51fd\u6570\u5fc5\u987b\u8fd9\u6837\u5199\u3002\u4e00\u4e2a\u6784\u9020\u51fd\u6570\u6c38\u8fdc\u6ca1\u6709\u8fd4\u56de\u503c\uff0c\u4e5f\u4e0d\u7528\u58f0\u660evoid\uff0c\u5c31\u50cf\u6211\u4eec\u5728\u524d\u9762\u7684\u4f8b\u5b50\u4e2d\u770b\u5230\u7684\u3002\u6790\u6784\u51fd\u6570Destructor \u5b8c\u6210\u76f8\u53cd\u7684\u529f\u80fd\u3002\u5b83\u5728objects\u88ab\u4ece\u5185\u5b58\u4e2d\u91ca\u653e\u7684\u65f6\u5019\u88ab\u81ea\u52a8\u8c03\u7528\u3002\u91ca\u653e\u53ef\u80fd\u662f\u56e0\u4e3a\u5b83\u5b58\u5728\u7684\u8303\u56f4\u5df2\u7ecf\u7ed3\u675f\u4e86\uff08\u4f8b\u5982\uff0c\u5982\u679cobject\u88ab\u5b9a\u4e49\u4e3a\u4e00\u4e2a\u51fd\u6570\u5185\u7684\u672c\u5730\uff08local\uff09\u5bf9\u8c61\u53d8\u91cf\uff0c\u800c\u8be5\u51fd\u6570\u7ed3\u675f\u4e86\uff09\uff1b\u6216\u8005\u662f\u56e0\u4e3a\u5b83\u662f\u4e00\u4e2a\u52a8\u6001\u5206\u914d\u7684\u5bf9\u8c61\uff0c\u800c\u88ab\u4f7f\u7528\u64cd\u4f5c\u7b26delete\u91ca\u653e\u4e86\u3002\u6790\u6784\u51fd\u6570\u5fc5\u987b\u4e0eclass\u540c\u540d\uff0c\u52a0\u6c34\u6ce2\u53f7tilde (~) \u524d\u7f00\uff0c\u5fc5\u987b\u65e0\u8fd4\u56de\u503c\u3002\u6790\u6784\u51fd\u6570\u7279\u522b\u9002\u7528\u4e8e\u5f53\u4e00\u4e2a\u5bf9\u8c61\u88ab\u52a8\u6001\u5206\u522b\u5185\u5b58\u7a7a\u95f4\uff0c\u800c\u5728\u5bf9\u8c61\u88ab\u9500\u6bc1\u7684\u65f6\u6211\u4eec\u5e0c\u671b\u91ca\u653e\u5b83\u6240\u5360\u7528\u7684\u7a7a\u95f4\u7684\u65f6\u5019\u3002\u4f8b\u5982\uff1a \/\/ example on constructors and destructors #include <iostream.h> class CRectangle { int *width, *height; public: CRectangle (int,int); ~CRectangle (); int area (void) {return (*width * *height);} }; CRectangle::CRectangle (int a, int b) { width = new int; height = new int; *width = a; *height = b; } CRectangle::~CRectangle () { delete width; delete height; } int main () { CRectangle rect (3,4), rectb (5,6); cout << \"rect area: \" << rect.area() << endl; cout << \"rectb area: \" << rectb.area() << endl; return 0; } rect area: 12
rectb area: 30\u6784\u9020\u51fd\u6570\u91cd\u8f7d(Overloading Constructors)\u50cf\u5176\u5b83\u51fd\u6570\u4e00\u6837\uff0c\u4e00\u4e2a\u6784\u9020\u51fd\u6570\u4e5f\u53ef\u4ee5\u88ab\u591a\u6b21\u91cd\u8f7d(overload)\u4e3a\u540c\u6837\u540d\u5b57\u7684\u51fd\u6570\uff0c\u4f46\u6709\u4e0d\u540c\u7684\u53c2\u6570\u7c7b\u578b\u548c\u4e2a\u6570\u3002\u8bb0\u4f4f\uff0c\u7f16\u8bd1\u5668\u4f1a\u8c03\u7528\u4e0e\u5728\u8c03\u7528\u65f6\u523b\u8981\u6c42\u7684\u53c2\u6570\u7c7b\u578b\u548c\u4e2a\u6570\u4e00\u6837\u7684\u90a3\u4e2a\u51fd\u6570(Section 2.3, Functions-II)\u3002\u5728\u8fd9\u91cc\u5219\u662f\u8c03\u7528\u4e0e\u7c7b\u5bf9\u8c61\u88ab\u58f0\u660e\u65f6\u4e00\u6837\u7684\u90a3\u4e2a\u6784\u9020\u51fd\u6570\u3002\u5b9e\u9645\u4e0a\uff0c\u5f53\u6211\u4eec\u5b9a\u4e49\u4e00\u4e2aclass\u800c\u6ca1\u6709\u660e\u786e\u5b9a\u4e49\u6784\u9020\u51fd\u6570\u7684\u65f6\u5019\uff0c\u7f16\u8bd1\u5668\u4f1a\u81ea\u52a8\u5047\u8bbe\u4e24\u4e2a\u91cd\u8f7d\u7684\u6784\u9020\u51fd\u6570 (\u9ed8\u8ba4\u6784\u9020\u51fd\u6570\"default constructor\" \u548c\u590d\u5236\u6784\u9020\u51fd\u6570\"copy constructor\")\u3002\u4f8b\u5982\uff0c\u5bf9\u4ee5\u4e0bclass\uff1a class CExample {
public:
int a,b,c;
void multiply (int n, int m) { a=n; b=m; c=a*b; };
};
\u6ca1\u6709\u5b9a\u4e49\u6784\u9020\u51fd\u6570\uff0c\u7f16\u8bd1\u5668\u81ea\u52a8\u5047\u8bbe\u5b83\u6709\u4ee5\u4e0bconstructor \u6210\u5458\u51fd\u6570\uff1aEmpty constructor\u5b83\u662f\u4e00\u4e2a\u6ca1\u6709\u4efb\u4f55\u53c2\u6570\u7684\u6784\u9020\u51fd\u6570\uff0c\u88ab\u5b9a\u4e49\u4e3anop (\u6ca1\u6709\u8bed\u53e5)\u3002\u5b83\u4ec0\u4e48\u90fd\u4e0d\u505a\u3002CExample::CExample () { };Copy constructor\u5b83\u662f\u4e00\u4e2a\u53ea\u6709\u4e00\u4e2a\u53c2\u6570\u7684\u6784\u9020\u51fd\u6570\uff0c\u8be5\u53c2\u6570\u662f\u8fd9\u4e2aclass\u7684\u4e00\u4e2a\u5bf9\u8c61\uff0c\u8fd9\u4e2a\u51fd\u6570\u7684\u529f\u80fd\u662f\u5c06\u88ab\u4f20\u5165\u7684\u5bf9\u8c61\uff08object\uff09\u7684\u6240\u6709\u975e\u9759\u6001\uff08non-static\uff09\u6210\u5458\u53d8\u91cf\u7684\u503c\u90fd\u590d\u5236\u7ed9\u81ea\u8eab\u8fd9\u4e2aobject\u3002 CExample::CExample (const CExample& rv) {
a=rv.a; b=rv.b; c=rv.c;
}
\u5fc5\u987b\u6ce8\u610f\uff1a<\/strong>\u8fd9\u4e24\u4e2a\u9ed8\u8ba4\u6784\u9020\u51fd\u6570\uff08empty construction \u548c copy constructor \uff09\u53ea\u6709\u5728\u6ca1\u6709\u5176\u5b83\u6784\u9020\u51fd\u6570\u88ab\u660e\u786e\u5b9a\u4e49\u7684\u60c5\u51b5\u4e0b\u624d\u5b58\u5728\u3002\u5982\u679c\u4efb\u4f55\u5176\u5b83\u6709\u4efb\u610f\u53c2\u6570\u7684\u6784\u9020\u51fd\u6570\u88ab\u5b9a\u4e49\u4e86\uff0c\u8fd9\u4e24\u4e2a\u6784\u9020\u51fd\u6570\u5c31\u90fd\u4e0d\u5b58\u5728\u4e86\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u5982\u679c\u4f60\u60f3\u8981\u6709empty construction \u548c copy constructor \uff0c\u5c31\u5fc5\u9700\u8981\u81ea\u5df1\u5b9a\u4e49\u5b83\u4eec\u3002\u5f53\u7136\uff0c\u5982\u679c\u4f60\u4e5f\u53ef\u4ee5\u91cd\u8f7dclass\u7684\u6784\u9020\u51fd\u6570\uff0c\u5b9a\u4e49\u6709\u4e0d\u540c\u7684\u53c2\u6570\u6216\u5b8c\u5168\u6ca1\u6709\u53c2\u6570\u7684\u6784\u9020\u51fd\u6570\uff0c\u89c1\u5982\u4e0b\u4f8b\u5b50\uff1a \/\/ overloading class constructors #include <iostream.h> Class CRectangle { int width, height; public: CRectangle (); CRectangle (int,int); int area (void) {return (width*height);} }; CRectangle::CRectangle () { width = 5; height = 5; } CRectangle::CRectangle (int a, int b) { width = a; height = b; } int main () { CRectangle rect (3,4); CRectangle rectb; cout << \"rect area: \" << rect.area() << endl; cout << \"rectb area: \" << rectb.area() << endl; } rect area: 12
rectb area: 25\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0crectb \u88ab\u58f0\u660e\u7684\u65f6\u5019\u6ca1\u6709\u53c2\u6570\uff0c\u6240\u4ee5\u5b83\u88ab\u4f7f\u7528\u6ca1\u6709\u53c2\u6570\u7684\u6784\u9020\u51fd\u6570\u8fdb\u884c\u521d\u59cb\u5316\uff0c\u4e5f\u5c31\u662fwidth \u548cheight \u90fd\u88ab\u8d4b\u503c\u4e3a5\u3002\u6ce8\u610f<\/strong>\u5728\u6211\u4eec\u58f0\u660e\u4e00\u4e2a\u65b0\u7684object\u7684\u65f6\u5019\uff0c\u5982\u679c\u4e0d\u60f3\u4f20\u5165\u53c2\u6570\uff0c\u5219\u4e0d\u9700\u8981\u5199\u62ec\u53f7()\uff1aCRectangle rectb; \/\/ right
CRectangle rectb(); \/\/ wrong!
\u7c7b\u7684\u6307\u9488(Pointers to classes)\u7c7b\u4e5f\u662f\u53ef\u4ee5\u6709\u6307\u9488\u7684\uff0c\u8981\u5b9a\u4e49\u7c7b\u7684\u6307\u9488\uff0c\u6211\u4eec\u53ea\u9700\u8981\u8ba4\u8bc6\u5230\uff0c\u7c7b\u4e00\u65e6\u88ab\u5b9a\u4e49\u5c31\u6210\u4e3a\u4e00\u79cd\u6709\u6548\u7684\u6570\u636e\u7c7b\u578b\uff0c\u56e0\u6b64\u53ea\u9700\u8981\u7528\u7c7b\u7684\u540d\u5b57\u4f5c\u4e3a\u6307\u9488\u7684\u540d\u5b57\u5c31\u53ef\u4ee5\u4e86\u3002\u4f8b\u5982\uff1aCRectangle * prect;\u662f\u4e00\u4e2a\u6307\u5411class CRectangle\u7c7b\u578b\u7684\u5bf9\u8c61\u7684\u6307\u9488\u3002\u5c31\u50cf\u6570\u636e\u673a\u6784\u4e2d\u7684\u60c5\u51b5\u4e00\u6837\uff0c\u8981\u60f3\u76f4\u63a5\u5f15\u7528\u4e00\u4e2a\u7531\u6307\u9488\u6307\u5411\u7684\u5bf9\u8c61(object)\u4e2d\u7684\u6210\u5458\uff0c\u9700\u8981\u4f7f\u7528\u64cd\u4f5c\u7b26 ->\u3002\u8fd9\u91cc\u662f\u4e00\u4e2a\u4f8b\u5b50\uff0c\u663e\u793a\u4e86\u51e0\u79cd\u53ef\u80fd\u51fa\u73b0\u7684\u60c5\u51b5\uff1a \/\/ pointer to classes example #include <iostream.h> class CRectangle { int width, height; public: void set_values (int, int); int area (void) {return (width * height);} }; void CRectangle::set_values (int a, int b) { width = a; height = b; } int main () { CRectangle a, *b, *c; CRectangle * d = new CRectangle[2]; b= new CRectangle; c= &a; a.set_values (1,2); b->set_values (3,4); d->set_values (5,6); d[1].set_values (7,8); cout << \"a area: \" << a.area() << endl; cout << \"*b area: \" << b->area() << endl; cout << \"*c area: \" << c->area() << endl; cout << \"d[0] area: \" << d[0].area() << endl; cout << \"d[1] area: \" << d[1].area() << endl; return 0; } a area: 2
*b area: 12
*c area: 2
d[0] area: 30
d[1] area: 56\u4ee5\u4e0b\u662f\u600e\u6837\u8bfb\u524d\u9762\u4f8b\u5b50\u4e2d\u51fa\u73b0\u7684\u4e00\u4e9b\u6307\u9488\u548c\u7c7b\u64cd\u4f5c\u7b26 (*, &, ., ->, [ ])\uff1a*x \u8bfb\u4f5c: pointed by x \uff08\u7531x\u6307\u5411\u7684\uff09&x \u8bfb\u4f5c: address of x\uff08x\u7684\u5730\u5740\uff09x.y \u8bfb\u4f5c: member y of object x \uff08\u5bf9\u8c61x\u7684\u6210\u5458y\uff09(*x).y \u8bfb\u4f5c: member y of object pointed by x\uff08\u7531x\u6307\u5411\u7684\u5bf9\u8c61\u7684\u6210\u5458y\uff09x->y \u8bfb\u4f5c: member y of object pointed by x (\u540c\u4e0a\u4e00\u4e2a\u7b49\u4ef7)x[0] \u8bfb\u4f5c: first object pointed by x\uff08\u7531x\u6307\u5411\u7684\u7b2c\u4e00\u4e2a\u5bf9\u8c61\uff09x[1] \u8bfb\u4f5c: second object pointed by x\uff08\u7531x\u6307\u5411\u7684\u7b2c\u4e8c\u4e2a\u5bf9\u8c61\uff09x[n] \u8bfb\u4f5c: (n+1)th object pointed by x\uff08\u7531x\u6307\u5411\u7684\u7b2cn+1\u4e2a\u5bf9\u8c61\uff09\u5728\u7ee7\u7eed\u5411\u4e0b\u9605\u8bfb\u4e4b\u524d\uff0c\u4e00\u5b9a\u8981\u786e\u5b9a\u4f60\u660e\u767d\u6240\u6709\u8fd9\u4e9b\u7684\u903b\u8f91\u542b\u4e49\u3002\u5982\u679c\u4f60\u8fd8\u6709\u7591\u95ee\uff0c\u518d\u8bfb\u4e00\u904d\u8fd9\u4e00\u7b11\u8282\uff0c\u6216\u8005\u540c\u65f6\u53c2\u8003 \u5c0f\u8282 \"3.3, \u6307\u9488(Pointers)\" \u548c \"3.5, \u6570\u636e\u7ed3\u6784(Structures)\".
\u7531\u5173\u952e\u5b57struct\u548cunion\u5b9a\u4e49\u7684\u7c7b\u7c7b\u4e0d\u4ec5\u53ef\u4ee5\u7528\u5173\u952e\u5b57class\u6765\u5b9a\u4e49\uff0c\u4e5f\u53ef\u4ee5\u7528struct\u6216union\u6765\u5b9a\u4e49\u3002
\u56e0\u4e3a\u5728C++\u4e2d\u7c7b\u548c\u6570\u636e\u7ed3\u6784\u7684\u6982\u5ff5\u592a\u76f8\u4f3c\u4e86\uff0c\u6240\u4ee5\u8fd9\u4e24\u4e2a\u5173\u952e\u5b57struct\u548cclass\u7684\u4f5c\u7528\u51e0\u4e4e\u662f\u4e00\u6837\u7684\uff08\u4e5f\u5c31\u662f\u8bf4\u5728C++\u4e2dstruct\u5b9a\u4e49\u7684\u7c7b\u4e5f\u53ef\u4ee5\u6709\u6210\u5458\u51fd\u6570\uff0c\u800c\u4e0d\u4ec5\u4ec5\u6709\u6570\u636e\u6210\u5458)\u3002\u4e24\u8005\u5b9a\u4e49\u7684\u7c7b\u7684\u552f\u4e00\u533a\u522b\u5728\u4e8e\u7531class\u5b9a\u4e49\u7684\u7c7b\u6240\u6709\u6210\u5458\u7684\u9ed8\u8ba4\u8bbf\u95ee\u6743\u9650\u4e3aprivate\uff0c\u800cstruct\u5b9a\u4e49\u7684\u7c7b\u6240\u6709\u6210\u5458\u9ed8\u8ba4\u8bbf\u95ee\u6743\u9650\u4e3apublic\u3002\u9664\u6b64\u4e4b\u5916\uff0c\u4e24\u4e2a\u5173\u952e\u5b57\u7684\u4f5c\u7528\u662f\u76f8\u540c\u7684\u3002union\u7684\u6982\u5ff5\u4e0estruct\u548cclass\u5b9a\u4e49\u7684\u7c7b\u4e0d\u540c\uff0c \u56e0\u4e3aunion\u5728\u540c\u4e00\u65f6\u95f4\u53ea\u80fd\u5b58\u50a8\u4e00\u4e2a\u6570\u636e\u6210\u5458\u3002\u4f46\u662f\u7531union\u5b9a\u4e49\u7684\u7c7b\u4e5f\u662f\u53ef\u4ee5\u6709\u6210\u5458\u51fd\u6570\u7684\u3002union\u5b9a\u4e49\u7684\u7c7b\u8bbf\u95ee\u6743\u9650\u9ed8\u8ba4\u4e3apublic\u3002<\/code><\/p>\n","protected":false},"excerpt":{"rendered":"