forked from zyb0408/zyb0408.github.io
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy path2019-01-12-C++类与对象.html
1309 lines (754 loc) · 49.1 KB
/
2019-01-12-C++类与对象.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<!DOCTYPE html>
<html class="theme-next pisces use-motion" lang="zh-Hans">
<head><meta name="generator" content="Hexo 3.8.0">
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<meta name="theme-color" content="#222">
<meta http-equiv="Cache-Control" content="no-transform">
<meta http-equiv="Cache-Control" content="no-siteapp">
<link href="/lib/fancybox/source/jquery.fancybox.css?v=2.1.5" rel="stylesheet" type="text/css">
<link href="/lib/font-awesome/css/font-awesome.min.css?v=4.6.2" rel="stylesheet" type="text/css">
<link href="/css/main.css?v=5.1.4" rel="stylesheet" type="text/css">
<link rel="icon" type="image/png" sizes="32x32" href="/images/favicon-32x32-next.png?v=5.1.4">
<meta name="keywords" content="C++,">
<meta name="description" content="类定义1234567class 类名&#123; private: //数据成员或者成员函数的声明 public: //成员函数或者数据成员的说明&#125;; 例子：日期类的说明：123456789class TDate&#123; public: void SetDate(int y, int m, int d); in">
<meta name="keywords" content="C++">
<meta property="og:type" content="article">
<meta property="og:title" content="C++类与对象">
<meta property="og:url" content="https://zyb0408.github.io/2019-01-12-C++类与对象.html">
<meta property="og:site_name" content="小蜜蜂">
<meta property="og:description" content="类定义1234567class 类名&#123; private: //数据成员或者成员函数的声明 public: //成员函数或者数据成员的说明&#125;; 例子：日期类的说明：123456789class TDate&#123; public: void SetDate(int y, int m, int d); in">
<meta property="og:locale" content="zh-Hans">
<meta property="og:updated_time" content="2019-01-17T06:38:13.447Z">
<meta name="twitter:card" content="summary">
<meta name="twitter:title" content="C++类与对象">
<meta name="twitter:description" content="类定义1234567class 类名&#123; private: //数据成员或者成员函数的声明 public: //成员函数或者数据成员的说明&#125;; 例子：日期类的说明：123456789class TDate&#123; public: void SetDate(int y, int m, int d); in">
<script type="text/javascript" id="hexo.configurations">
var NexT = window.NexT || {};
var CONFIG = {
root: '/',
scheme: 'Pisces',
version: '5.1.4',
sidebar: {"position":"left","display":"post","offset":12,"b2t":false,"scrollpercent":true,"onmobile":false},
fancybox: true,
tabs: true,
motion: {"enable":true,"async":false,"transition":{"post_block":"fadeIn","post_header":"slideDownIn","post_body":"slideDownIn","coll_header":"slideLeftIn","sidebar":"slideUpIn"}},
duoshuo: {
userId: '0',
author: '博主'
},
algolia: {
applicationID: '',
apiKey: '',
indexName: '',
hits: {"per_page":10},
labels: {"input_placeholder":"Search for Posts","hits_empty":"We didn't find any results for the search: ${query}","hits_stats":"${hits} results found in ${time} ms"}
}
};
</script>
<link rel="canonical" href="https://zyb0408.github.io/2019-01-12-C++类与对象.html">
<title>C++类与对象 | 小蜜蜂</title>
</head>
<body itemscope="" itemtype="http://schema.org/WebPage" lang="zh-Hans">
<div class="container sidebar-position-left page-post-detail">
<div class="headband"></div>
<header id="header" class="header" itemscope="" itemtype="http://schema.org/WPHeader">
<div class="header-inner"><div class="site-brand-wrapper">
<div class="site-meta custom-logo">
<div class="custom-logo-site-title">
<a href="/" class="brand" rel="start">
<span class="logo-line-before"><i></i></span>
<span class="site-title">小蜜蜂</span>
<span class="logo-line-after"><i></i></span>
</a>
</div>
<p class="site-subtitle">Don't Hack Me</p>
</div>
<div class="site-nav-toggle">
<button>
<span class="btn-bar"></span>
<span class="btn-bar"></span>
<span class="btn-bar"></span>
</button>
</div>
</div>
<nav class="site-nav">
<ul id="menu" class="menu">
<li class="menu-item menu-item-home">
<a href="/" rel="section">
<i class="menu-item-icon fa fa-fw fa-home"></i> <br>
首页
</a>
</li>
<li class="menu-item menu-item-about">
<a href="/about/" rel="section">
<i class="menu-item-icon fa fa-fw fa-user"></i> <br>
关于
</a>
</li>
<li class="menu-item menu-item-tags">
<a href="/tags/" rel="section">
<i class="menu-item-icon fa fa-fw fa-tags"></i> <br>
标签
</a>
</li>
<li class="menu-item menu-item-categories">
<a href="/categories/" rel="section">
<i class="menu-item-icon fa fa-fw fa-th"></i> <br>
分类
</a>
</li>
<li class="menu-item menu-item-archives">
<a href="/archives/" rel="section">
<i class="menu-item-icon fa fa-fw fa-archive"></i> <br>
归档
</a>
</li>
<li class="menu-item menu-item-search">
<a href="javascript:;" class="popup-trigger">
<i class="menu-item-icon fa fa-search fa-fw"></i> <br>
搜索
</a>
</li>
</ul>
<div class="site-search">
<div class="popup search-popup local-search-popup">
<div class="local-search-header clearfix">
<span class="search-icon">
<i class="fa fa-search"></i>
</span>
<span class="popup-btn-close">
<i class="fa fa-times-circle"></i>
</span>
<div class="local-search-input-wrapper">
<input autocomplete="off" placeholder="搜索..." spellcheck="false" type="text" id="local-search-input">
</div>
</div>
<div id="local-search-result"></div>
</div>
</div>
</nav>
</div>
</header>
<main id="main" class="main">
<div class="main-inner">
<div class="content-wrap">
<div id="content" class="content">
<div id="posts" class="posts-expand">
<article class="post post-type-normal" itemscope="" itemtype="http://schema.org/Article">
<div class="post-block">
<link itemprop="mainEntityOfPage" href="https://zyb0408.github.io/2019-01-12-C++类与对象.html">
<span hidden itemprop="author" itemscope="" itemtype="http://schema.org/Person">
<meta itemprop="name" content="小蜜蜂">
<meta itemprop="description" content="">
<meta itemprop="image" content="/images/favicon-32x32-next.png">
</span>
<span hidden itemprop="publisher" itemscope="" itemtype="http://schema.org/Organization">
<meta itemprop="name" content="小蜜蜂">
</span>
<header class="post-header">
<h1 class="post-title" itemprop="name headline">C++类与对象</h1>
<div class="post-meta">
<span class="post-time">
<span class="post-meta-item-icon">
<i class="fa fa-calendar-o"></i>
</span>
<span class="post-meta-item-text">发表于</span>
<time title="创建于" itemprop="dateCreated datePublished" datetime="2019-01-12T20:53:29+08:00">
2019-01-12
</time>
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-calendar-check-o"></i>
</span>
<span class="post-meta-item-text">更新于:</span>
<time title="更新于" itemprop="dateModified" datetime="2019-01-17T14:38:13+08:00">
2019-01-17
</time>
</span>
<span class="post-category">
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-folder-o"></i>
</span>
<span class="post-meta-item-text">分类于</span>
<span itemprop="about" itemscope="" itemtype="http://schema.org/Thing">
<a href="/categories/C/" itemprop="url" rel="index">
<span itemprop="name">C++</span>
</a>
</span>
</span>
<span class="post-meta-divider">|</span>
<span class="page-pv"><i class="fa fa-file-o"></i>
<span class="busuanzi-value" id="busuanzi_value_page_pv"></span>
</span>
<div class="post-wordcount">
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-file-word-o"></i>
</span>
<span class="post-meta-item-text">字数统计:</span>
<span title="字数统计">
1.3k
</span>
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-clock-o"></i>
</span>
<span class="post-meta-item-text">阅读时长 ≈</span>
<span title="阅读时长">
4
</span>
</div>
</div>
</header>
<div class="post-body" itemprop="articleBody">
<div>
<div>
<div style="text-align:center;color: #636363;font-size:14px;letter-spacing: 10px">���Ľ�����<i class="fa fa-bell"></i>��л�����Ķ�</div>
</div>
</div>
<h1 id="类定义"><a href="#类定义" class="headerlink" title="类定义"></a>类定义</h1><figure class="highlight actionscript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">class</span> 类名</span></span><br><span class="line"><span class="class"></span>{</span><br><span class="line"> <span class="keyword">private</span>:</span><br><span class="line"> <span class="comment">//数据成员或者成员函数的声明</span></span><br><span class="line"> <span class="keyword">public</span>:</span><br><span class="line"> <span class="comment">//成员函数或者数据成员的说明</span></span><br><span class="line">};</span><br></pre></td></tr></table></figure>
<p>例子：<br>日期类的说明：<br><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">TDate</span></span></span><br><span class="line"><span class="class">{</span></span><br><span class="line"> <span class="keyword">public</span>:</span><br><span class="line"> <span class="function"><span class="keyword">void</span> <span class="title">SetDate</span><span class="params">(<span class="keyword">int</span> y, <span class="keyword">int</span> m, <span class="keyword">int</span> d)</span></span>;</span><br><span class="line"> <span class="function"><span class="keyword">int</span> <span class="title">IsLeapYear</span><span class="params">()</span></span>;</span><br><span class="line"> <span class="function"><span class="keyword">void</span> <span class="title">Print</span><span class="params">()</span></span>;</span><br><span class="line"> <span class="keyword">private</span>:</span><br><span class="line"> <span class="keyword">int</span> year,month,day;</span><br><span class="line">};</span><br></pre></td></tr></table></figure></p>
<p>日期类的实现部分如下：<br><figure class="highlight processing"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">void</span> TDate::SetDate(<span class="built_in">int</span> y, <span class="built_in">int</span> m, <span class="built_in">int</span> d)</span><br><span class="line">{</span><br><span class="line"> <span class="built_in">year</span> = y;</span><br><span class="line"> <span class="built_in">month</span> = m;</span><br><span class="line"> <span class="built_in">day</span> = d;</span><br><span class="line">}</span><br><span class="line"><span class="built_in">int</span> TDate::IsLeapYear()</span><br><span class="line">{</span><br><span class="line"> <span class="keyword">return</span> (<span class="built_in">year</span>%<span class="number">4</span> == <span class="number">0</span> && <span class="built_in">year</span>%<span class="number">100</span> != <span class="number">0</span>) || (<span class="built_in">year</span>%<span class="number">400</span> == <span class="number">0</span>);</span><br><span class="line">}</span><br><span class="line"><span class="keyword">void</span> TDate::Print()</span><br><span class="line">{</span><br><span class="line"> cout<<<span class="built_in">year</span><<<span class="string">"."</span><<<span class="built_in">month</span><<<span class="string">"."</span><<<span class="built_in">day</span><<endl;</span><br><span class="line">}</span><br></pre></td></tr></table></figure></p>
<h2 id="注意事项"><a href="#注意事项" class="headerlink" title="注意事项"></a>注意事项</h2><ul>
<li>类体中不允许对所定义的数据成员进行初始化</li>
<li><p>类中的数据成员的类型可以是任意的，包含int，float，char，数组，指针和引用等，也可以是对象。另一个类的对象可以作为该类的成员，但是自身类的对象是不可以的，而自身类的指针或者引用是可以的。当一个类的对象作为这个类的成员时，如果另一个类定义在后面，则需要提前说明，这种说明称为引用性说明。</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">N</span>;</span></span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">M</span></span></span><br><span class="line"><span class="class">{</span></span><br><span class="line"> <span class="keyword">public</span>:</span><br><span class="line"> ...</span><br><span class="line"> <span class="keyword">private</span>:</span><br><span class="line"> N n;<span class="comment">//n是N的对象</span></span><br><span class="line">};</span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">N</span>{</span></span><br><span class="line"> <span class="keyword">public</span>:</span><br><span class="line"> ...</span><br><span class="line"> <span class="keyword">private</span>:</span><br><span class="line"> ...</span><br><span class="line">};</span><br></pre></td></tr></table></figure>
</li>
<li><p>一般在类体中先说明公有成员，这是用户所关心的；后说明私有成员。一般按照类型的大小从小到大说明，这样可以提高空间利用效率。</p>
</li>
<li>通常习惯将类定义的说明部分放到一个头文件中。</li>
</ul>
<h1 id="对象"><a href="#对象" class="headerlink" title="对象"></a>对象</h1><h2 id="对象定义"><a href="#对象定义" class="headerlink" title="对象定义"></a>对象定义</h2><figure class="highlight c++"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">类名 对象名的列表;</span><br></pre></td></tr></table></figure>
<p>例子：<br><figure class="highlight c++"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">TDate data1, date2, *Pdate, date[<span class="number">10</span>];</span><br></pre></td></tr></table></figure></p>
<h2 id="对象成员的表示方法"><a href="#对象成员的表示方法" class="headerlink" title="对象成员的表示方法"></a>对象成员的表示方法</h2><figure class="highlight clean"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//一般对象的成员表示</span></span><br><span class="line">对象名.成员名</span><br><span class="line">对象名.成员名(参数列表)</span><br><span class="line"><span class="comment">//指针对象的指针成员表示</span></span><br><span class="line">对象指针名->成员名</span><br><span class="line">对象指针名->成员名(参数列表)</span><br></pre></td></tr></table></figure>
<p>例子：<br><figure class="highlight processing"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line">date1.<span class="built_in">year</span>,date1.<span class="built_in">month</span></span><br><span class="line">date1.SetDate(<span class="built_in">int</span> y, <span class="built_in">int</span> m,<span class="built_in">int</span> d)</span><br><span class="line"><span class="comment">//指针</span></span><br><span class="line">Pdate-><span class="built_in">year</span>,Pdate-><span class="built_in">month</span></span><br><span class="line">(* Pdate).<span class="built_in">year</span></span><br><span class="line">Pdate->SetDate(y,m,d)</span><br><span class="line">(* Pdate).SetDate(y,m,d)</span><br></pre></td></tr></table></figure></p>
<h1 id="对象初始化与回收"><a href="#对象初始化与回收" class="headerlink" title="对象初始化与回收"></a>对象初始化与回收</h1><p>对象定义完了之后就是对象的初始化了。<br><strong> 初始化主要是通过类中的初始化函数完成的。这个初始化函数叫<code>构造函数</code>。</strong><br><strong> 对象用完之后的回收用的是类定义中的反初始化函数，叫做<code>析构函数</code>。</strong></p>
<h3 id="构造函数特点"><a href="#构造函数特点" class="headerlink" title="构造函数特点"></a>构造函数特点</h3><ul>
<li>构造函数是成员函数，函数体可以写在类体内，也可以写在类体外</li>
<li>构造函数是一个特殊的成员函数，该函数的名字与类名相同，函数不指定返回值类型。它有返回值，该值由系统内部使用。该函数可以没有参数，也可以有参数。</li>
<li>构造函数可以重载，即可以定义多个参数个数不同的函数。</li>
<li>程序中一般不直接调用构造函数，在创建对象时系统自动调用构造函数。</li>
</ul>
<h3 id="析构函数的特点"><a href="#析构函数的特点" class="headerlink" title="析构函数的特点"></a>析构函数的特点</h3><ul>
<li>析构函数是成员函数，函数体可以写在类体内，也可以写在类体外</li>
<li>也是一个特殊的成员函数，名字与类名相同，并在前面加一个<code>~</code>字符。用于与构造函数加以区别。不指定数据类型，并且没有参数</li>
<li>一个类中只能有一个析构函数</li>
<li>通常由系统自动调用。下面两种情况下，析构会自动调用<ul>
<li>如果一个对象呗定义在一个函数体内，则当这个函数结束时，即该对象结束生存，系统调用析构释放该对象</li>
<li>如果一个对象是使用new运算符被动创建的，则在使用delete运算释放它时，delete将会调用析构</li>
</ul>
</li>
</ul>
<h3 id="默认构造函数与默认析构函数"><a href="#默认构造函数与默认析构函数" class="headerlink" title="默认构造函数与默认析构函数"></a>默认构造函数与默认析构函数</h3><p>没有参数的构造函数成为默认构造函数。</p>
<ul>
<li>一种是系统默认的</li>
<li>一种是程序员自己定义的</li>
</ul>
<p><strong> 创建对象时都要调用构造函数进行对象初始化。</strong></p>
<h3 id="复制构造函数"><a href="#复制构造函数" class="headerlink" title="复制构造函数"></a>复制构造函数</h3><p><code>复制构造函数</code>是用一个已知的对象来创造另一个对象，而新对象与已知的对象的数据成员的值可以相同，也可以不同。<br>复制构造函数除了具有之前讲过的带参构造函数的特性外，它只有一个参数，并且是对象引用。<br>格式如下：<br><figure class="highlight 1c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">类名::复制构造函数名(类名 <span class="meta">&引用名)</span></span><br><span class="line">{</span><br><span class="line"> 函数体</span><br><span class="line">}；</span><br></pre></td></tr></table></figure></p>
<p>如果一个类中没有定义复制构造函数，系统会自动提供一个默认的复制构造函数，作为该类的公有成员，用来根据已知对象创建与其相同的新对象。<br>以下3中情况会调用复制构造函数来由一个对象初始化另一个对象。</p>
<ul>
<li>1.明确表示由一个对象初始化另一个对象时</li>
<li>2.当对象作为函数实参传递给函数形参时</li>
<li>3.当一个自动存储类对象作为函数返回时<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//1.</span></span><br><span class="line"><span class="function">TPoint <span class="title">P2</span><span class="params">(P1)</span></span>;</span><br><span class="line"><span class="comment">//2.</span></span><br><span class="line">P=f(N);</span><br><span class="line"><span class="comment">//3.</span></span><br><span class="line"><span class="keyword">return</span> R;</span><br></pre></td></tr></table></figure>
</li>
</ul>
</div>
<div>
<ul class="post-copyright">
<li class="post-copyright-author">
<strong>本文作者：</strong>
小蜜蜂
</li>
<li class="post-copyright-link">
<strong>本文链接：</strong>
<a href="https://zyb0408.github.io/2019-01-12-C++类与对象.html" title="C++类与对象">https://zyb0408.github.io/2019-01-12-C++类与对象.html</a>
</li>
<li class="post-copyright-license">
<strong>版权声明： </strong>
本博客所有文章除特别声明外，均采用 <a href="https://creativecommons.org/licenses/by-nc-sa/3.0/" rel="external nofollow" target="_blank">CC BY-NC-SA 3.0</a> 许可协议。转载请注明出处！
</li>
</ul>
</div>
<footer class="post-footer">
<div class="post-tags">
<a href="/tags/C/" rel="tag"># C++</a>
</div>
<div class="post-nav">
<div class="post-nav-next post-nav-item">
<a href="/2019-01-11-Linux学习.html" rel="next" title="Linux学习">
<i class="fa fa-chevron-left"></i> Linux学习
</a>
</div>
<span class="post-nav-divider"></span>
<div class="post-nav-prev post-nav-item">
<a href="/2019-01-13-C++成员函数的特性.html" rel="prev" title="C++成员函数的特性之【内外联函数】">
C++成员函数的特性之【内外联函数】 <i class="fa fa-chevron-right"></i>
</a>
</div>
</div>
</footer>
</div>
</article>
<div class="post-spread">
</div>
</div>
</div>
</div>
<div class="sidebar-toggle">
<div class="sidebar-toggle-line-wrap">
<span class="sidebar-toggle-line sidebar-toggle-line-first"></span>
<span class="sidebar-toggle-line sidebar-toggle-line-middle"></span>
<span class="sidebar-toggle-line sidebar-toggle-line-last"></span>
</div>
</div>
<aside id="sidebar" class="sidebar">
<div class="sidebar-inner">
<ul class="sidebar-nav motion-element">
<li class="sidebar-nav-toc sidebar-nav-active" data-target="post-toc-wrap">
文章目录
</li>
<li class="sidebar-nav-overview" data-target="site-overview-wrap">
站点概览
</li>
</ul>
<section class="site-overview-wrap sidebar-panel">
<div class="site-overview">
<div class="site-author motion-element" itemprop="author" itemscope="" itemtype="http://schema.org/Person">
<img class="site-author-image" itemprop="image" src="/images/favicon-32x32-next.png" alt="小蜜蜂">
<p class="site-author-name" itemprop="name">小蜜蜂</p>
<p class="site-description motion-element" itemprop="description">小蜜蜂学计算机</p>
</div>
<nav class="site-state motion-element">
<div class="site-state-item site-state-posts">
<a href="/archives/">
<span class="site-state-item-count">52</span>
<span class="site-state-item-name">日志</span>
</a>
</div>
<div class="site-state-item site-state-categories">
<a href="/categories/index.html">
<span class="site-state-item-count">18</span>
<span class="site-state-item-name">分类</span>
</a>
</div>
<div class="site-state-item site-state-tags">
<a href="/tags/index.html">
<span class="site-state-item-count">22</span>
<span class="site-state-item-name">标签</span>
</a>
</div>
</nav>
<div class="links-of-author motion-element">
<span class="links-of-author-item">
<a href="https://github.com/zyb0408" target="_blank" title="GitHub">
<i class="fa fa-fw fa-github"></i>GitHub</a>
</span>
</div>
<div class="links-of-blogroll motion-element links-of-blogroll-block">
<div class="links-of-blogroll-title">
<i class="fa fa-fw fa-link"></i>
Links
</div>
<ul class="links-of-blogroll-list">
<li class="links-of-blogroll-item">
<a href="https://dhupxd.github.io" title="学姐" target="_blank">学姐</a>
</li>
<li class="links-of-blogroll-item">
<a href="https://ztt001.github.io" title="学妹" target="_blank">学妹</a>
</li>
</ul>
</div>
</div>
</section>
<!--noindex-->
<section class="post-toc-wrap motion-element sidebar-panel sidebar-panel-active">
<div class="post-toc">
<div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-1"><a class="nav-link" href="#类定义"><span class="nav-number">1.</span> <span class="nav-text">类定义</span></a><ol class="nav-child"><li class="nav-item nav-level-2"><a class="nav-link" href="#注意事项"><span class="nav-number">1.1.</span> <span class="nav-text">注意事项</span></a></li></ol></li><li class="nav-item nav-level-1"><a class="nav-link" href="#对象"><span class="nav-number">2.</span> <span class="nav-text">对象</span></a><ol class="nav-child"><li class="nav-item nav-level-2"><a class="nav-link" href="#对象定义"><span class="nav-number">2.1.</span> <span class="nav-text">对象定义</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#对象成员的表示方法"><span class="nav-number">2.2.</span> <span class="nav-text">对象成员的表示方法</span></a></li></ol></li><li class="nav-item nav-level-1"><a class="nav-link" href="#对象初始化与回收"><span class="nav-number">3.</span> <span class="nav-text">对象初始化与回收</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#构造函数特点"><span class="nav-number">3.0.1.</span> <span class="nav-text">构造函数特点</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#析构函数的特点"><span class="nav-number">3.0.2.</span> <span class="nav-text">析构函数的特点</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#默认构造函数与默认析构函数"><span class="nav-number">3.0.3.</span> <span class="nav-text">默认构造函数与默认析构函数</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#复制构造函数"><span class="nav-number">3.0.4.</span> <span class="nav-text">复制构造函数</span></a></li></ol></li></ol></div>
</div>
</section>
<!--/noindex-->
</div>
</aside>
</div>
</main>
<footer id="footer" class="footer">
<div class="footer-inner">
<script async src="https://dn-lbstatics.qbox.me/busuanzi/2.3/busuanzi.pure.mini.js"></script>
<div class="copyright">© 2017 — <span itemprop="copyrightYear">2019</span>
<span class="with-love">
<i class="fa fa-user"></i>
</span>
<span class="author" itemprop="copyrightHolder">小蜜蜂</span>
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-area-chart"></i>
</span>
<span class="post-meta-item-text">Site words total count:</span>
<span title="Site words total count">88.8k</span>
</div>
<div class="powered-by">
<i class="fa fa-user-md"></i><span id="busuanzi_container_site_uv">
本站访客数:<span id="busuanzi_value_site_uv"></span>
</span>
</div>
<script>
var seconds = 1000;
var minutes = seconds * 60;
var hours = minutes * 60;
var days = hours * 24;
var years = days * 365;
var birthDay = Date.UTC(2017,09,17,00,00,00); // 这里设置建站时间
setInterval(function() {
var today = new Date();
var todayYear = today.getFullYear();
var todayMonth = today.getMonth()+1;
var todayDate = today.getDate();
var todayHour = today.getHours();
var todayMinute = today.getMinutes();
var todaySecond = today.getSeconds();
var now = Date.UTC(todayYear,todayMonth,todayDate,todayHour,todayMinute,todaySecond);
var diff = now - birthDay;
var diffYears = Math.floor(diff/years);
var diffDays = Math.floor((diff/days)-diffYears*365);
var diffHours = Math.floor((diff-(diffYears*365+diffDays)*days)/hours);
var diffMinutes = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours)/minutes);
var diffSeconds = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours-diffMinutes*minutes)/seconds);
document.getElementById('showDays').innerHTML="本站已运行 "+diffYears+" 年 "+diffDays+" 天 "+diffHours+" 小时 "+diffMinutes+" 分钟 "+diffSeconds+" 秒";
}, 1000);
</script>
<script async src="//busuanzi.ibruce.info/busuanzi/2.3/busuanzi.pure.mini.js">
</script>
<div class="busuanzi-count">
<script async src="https://dn-lbstatics.qbox.me/busuanzi/2.3/busuanzi.pure.mini.js"></script>
<span class="site-uv">
<i class="fa fa-user"></i>
<span class="busuanzi-value" id="busuanzi_value_site_uv"></span>
</span>
<span class="site-pv">
<i class="fa fa-eye"></i>
<span class="busuanzi-value" id="busuanzi_value_site_pv"></span>
</span>
</div>
</div>
</footer>
<div class="back-to-top">
<i class="fa fa-arrow-up"></i>
<span id="scrollpercent"><span>0</span>%</span>
</div>
</div>
<script type="text/javascript">
if (Object.prototype.toString.call(window.Promise) !== '[object Function]') {
window.Promise = null;
}
</script>
<script type="text/javascript" src="/lib/jquery/index.js?v=2.1.3"></script>
<script type="text/javascript" src="/lib/fastclick/lib/fastclick.min.js?v=1.0.6"></script>
<script type="text/javascript" src="/lib/jquery_lazyload/jquery.lazyload.js?v=1.9.7"></script>
<script type="text/javascript" src="/lib/velocity/velocity.min.js?v=1.2.1"></script>
<script type="text/javascript" src="/lib/velocity/velocity.ui.min.js?v=1.2.1"></script>
<script type="text/javascript" src="/lib/fancybox/source/jquery.fancybox.pack.js?v=2.1.5"></script>
<script type="text/javascript" src="/lib/canvas-nest/canvas-nest.min.js"></script>
<script type="text/javascript" src="/js/src/utils.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/motion.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/affix.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/schemes/pisces.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/scrollspy.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/post-details.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/bootstrap.js?v=5.1.4"></script>
<script type="text/javascript">
// Popup Window;
var isfetched = false;
var isXml = true;
// Search DB path;
var search_path = "search.xml";
if (search_path.length === 0) {
search_path = "search.xml";
} else if (/json$/i.test(search_path)) {
isXml = false;
}
var path = "/" + search_path;
// monitor main search box;
var onPopupClose = function (e) {
$('.popup').hide();
$('#local-search-input').val('');
$('.search-result-list').remove();
$('#no-result').remove();
$(".local-search-pop-overlay").remove();
$('body').css('overflow', '');
}
function proceedsearch() {
$("body")
.append('<div class="search-popup-overlay local-search-pop-overlay"></div>')
.css('overflow', 'hidden');
$('.search-popup-overlay').click(onPopupClose);
$('.popup').toggle();
var $localSearchInput = $('#local-search-input');
$localSearchInput.attr("autocapitalize", "none");
$localSearchInput.attr("autocorrect", "off");
$localSearchInput.focus();
}
// search function;