1 00:00:03,120 --> 00:00:08,430 Hello everyone in this session we will learn more about constructors in the last session. 2 00:00:08,430 --> 00:00:11,900 We learned what our constructors and how they are called. 3 00:00:11,910 --> 00:00:13,430 When we create an object. 4 00:00:13,650 --> 00:00:19,620 So we also learn that as soon as we create a class our default constructor is created and we can use 5 00:00:19,620 --> 00:00:25,710 the default constructor for initializing the object we can create our own constructor also. 6 00:00:25,830 --> 00:00:31,350 And as soon as we create our own constructor and build constructor is not visible to us anymore. 7 00:00:32,060 --> 00:00:32,680 Okay. 8 00:00:32,850 --> 00:00:43,660 So what happened is as soon as we create our class as soon as we create our class we get a few functions 9 00:00:43,660 --> 00:00:56,130 for free we will get a few functions for free so no one is default constructor. 10 00:00:56,160 --> 00:01:04,970 The second function that we will get for fee is called copy constructor. 11 00:01:05,080 --> 00:01:07,210 The third one is copy assignment operator 12 00:01:12,320 --> 00:01:16,850 and the fourth one is called our district that 13 00:01:21,040 --> 00:01:21,500 okay. 14 00:01:21,560 --> 00:01:27,860 So as soon as we create a class we will get a few functions for free. 15 00:01:27,860 --> 00:01:32,820 We have already started about a default constructor and what it does in this video. 16 00:01:32,880 --> 00:01:39,020 Our main focus will be on copy constructor and in the next videos we will learn about these two copy 17 00:01:39,020 --> 00:01:41,040 assignment operator and district. 18 00:01:41,210 --> 00:01:45,510 Okay so let's start to this topic which is a copy constructor. 19 00:01:45,650 --> 00:01:47,150 So what is a copy constructor. 20 00:01:47,150 --> 00:01:54,920 Let us first understand with the help of an example let us create two objects a student s one and let's 21 00:01:54,920 --> 00:01:59,120 say that all somebody stone ages 10 and somebody is hundred. 22 00:01:59,120 --> 00:02:00,580 So what will happen. 23 00:02:00,620 --> 00:02:04,190 Batman tries to construct a little bit called okay. 24 00:02:04,310 --> 00:02:07,530 Now let us create that object. 25 00:02:07,530 --> 00:02:18,900 Student as to in this case default constructor will be called Okay now I let him Our aim is very simple. 26 00:02:18,910 --> 00:02:21,890 I want to copy the value of S1 and to S2. 27 00:02:22,240 --> 00:02:22,850 Okay. 28 00:02:23,050 --> 00:02:24,670 So our aim is very simple. 29 00:02:24,730 --> 00:02:27,020 Copy the value of S went into S2. 30 00:02:27,070 --> 00:02:35,280 So what I want is is to age should be 10 and as to the number should be a hundred. 31 00:02:35,420 --> 00:02:37,800 Okay so how can we do this. 32 00:02:37,880 --> 00:02:49,540 So there is very simple we we will do like this is to dot set age and we will give input as as one dart 33 00:02:49,810 --> 00:02:50,440 get age 34 00:02:54,210 --> 00:03:04,740 and similarly S2 doctoral but is S1 daughter number. 35 00:03:04,990 --> 00:03:15,430 See if we will write as to what age is S1 Dark Age this line is wrong way because age is a private field 36 00:03:16,580 --> 00:03:22,010 age is a private field so if we want to do something if we want to do something with age we have to 37 00:03:22,010 --> 00:03:24,950 use public functions set age and get age. 38 00:03:24,950 --> 00:03:26,630 Okay rule number is public. 39 00:03:26,720 --> 00:03:29,840 So it will work fine okay. 40 00:03:29,870 --> 00:03:36,440 So if I want to copy the value of S1 into S2 I have to write these two lines I have to write these two 41 00:03:36,440 --> 00:03:40,510 lines explicitly okay. 42 00:03:41,420 --> 00:03:44,720 So we do not need to do this work explicitly. 43 00:03:44,720 --> 00:03:50,900 We have a constructor for doing this work and that constructor is called a copy constructor okay. 44 00:03:51,010 --> 00:04:02,050 So what copy constructor does is it creates the copy it creates an object which is copy of other object 45 00:04:02,490 --> 00:04:07,960 which is copy of either object. 46 00:04:07,990 --> 00:04:10,320 So this is the work of a copy concept. 47 00:04:11,050 --> 00:04:13,210 So let's let's take an example 48 00:04:16,330 --> 00:04:22,690 let's create an object first student S1 ages 10 the numbers ended. 49 00:04:22,770 --> 00:04:29,120 Now I want to make a copy of student S1 so the syntax is very simple. 50 00:04:29,190 --> 00:04:34,870 Student S2 and we will give S1 s better. 51 00:04:36,280 --> 00:04:42,370 Okay so what will happen the properties of the values of S1 will get copied into S2. 52 00:04:43,210 --> 00:04:50,760 So in this case better made price to constructively regard which we have created in the last radios 53 00:04:51,300 --> 00:04:58,790 and in this case copy constructor will be called Okay which will copy the value off as 1 and 2 S2. 54 00:04:58,790 --> 00:05:01,580 So how would this line will be interpreted. 55 00:05:01,580 --> 00:05:11,030 This line will internally look like this as one dot sorry is to not have a function student and input 56 00:05:11,030 --> 00:05:13,800 will be as one parameter will be S1. 57 00:05:14,040 --> 00:05:20,950 Okay so S1 is of type student s and is a barometer of type student. 58 00:05:21,140 --> 00:05:29,660 Now we have not created any constructor which takes one argument of type student as input Okay we have 59 00:05:29,660 --> 00:05:34,820 not made any constructor which takes one argument of type student but we are able to use it. 60 00:05:35,060 --> 00:05:41,280 How because as soon as we create a class copy construct base also created. 61 00:05:41,490 --> 00:05:44,370 Okay so what will the effect of these two lines. 62 00:05:44,640 --> 00:05:46,900 So the effect of this line is very simple. 63 00:05:48,260 --> 00:05:54,170 Age will be 10 and rule number will be entered. 64 00:05:54,290 --> 00:06:08,800 This is S1 and the effect of this line ages then rule number is hundred and this is Student 2 Okay now 65 00:06:08,800 --> 00:06:12,190 one thing here is since copy construct basic concept. 66 00:06:12,370 --> 00:06:15,330 It will be called only at the time of the creation of the object. 67 00:06:16,600 --> 00:06:18,310 Okay now let's see in called 68 00:06:28,020 --> 00:06:29,610 let's make an object string. 69 00:06:29,610 --> 00:06:34,160 That's 1 8 just in really embodies and read. 70 00:06:34,270 --> 00:06:37,210 So copy barometer based constructor will be guarded 71 00:06:43,280 --> 00:06:43,610 okay. 72 00:06:43,620 --> 00:06:53,620 We have created this Panama imitates constructor and let's spend something so we'll see out S1 73 00:06:56,490 --> 00:06:57,940 and let's call display function. 74 00:06:57,980 --> 00:07:01,560 So S1 dart display okay. 75 00:07:01,730 --> 00:07:13,690 So now make an object this object will be the copy of s an object and let's print this object onto the 76 00:07:13,690 --> 00:07:14,500 student as to 77 00:07:19,750 --> 00:07:21,650 as to not display 78 00:07:25,790 --> 00:07:29,040 so in this lane copy construct a little bit cold. 79 00:07:29,120 --> 00:07:31,780 And this court begins to produce in bold constructed. 80 00:07:32,350 --> 00:07:42,840 OK so this better imitates construct that is user defined Vermeer discussed it it is not so this bad 81 00:07:42,840 --> 00:07:46,230 imitates concept but is not given by class. 82 00:07:46,260 --> 00:07:49,290 We created this constructor Okay so user defined 83 00:07:52,510 --> 00:07:54,580 Okay so now let us turn this file 84 00:07:58,030 --> 00:08:03,460 so the value of this is getting printed paramedics construct based called construct with regard the 85 00:08:03,460 --> 00:08:08,150 value of age for student s on the stand and for us to do is also ten hundred and hundred the value from 86 00:08:08,160 --> 00:08:09,920 Lumberton also same. 87 00:08:10,030 --> 00:08:16,180 So one thing here is so one thing to note here is there is no constructor called a message for object 88 00:08:16,290 --> 00:08:22,420 as true because for us to copy constructor is called and we have not made our own copy construct but 89 00:08:22,660 --> 00:08:29,350 we are using the intended copy sector and in that inbuilt copy construct that there is no see out message. 90 00:08:29,350 --> 00:08:36,370 So that's why it see our message will appear for object as to so in this way we can use copy constructor 91 00:08:36,370 --> 00:08:38,050 to create copy of the object. 92 00:08:38,670 --> 00:08:39,230 Okay. 93 00:08:39,400 --> 00:08:43,950 So in this way we can use copy constructor to create copies of the object. 94 00:08:43,960 --> 00:08:47,230 Now here we have created objects statically. 95 00:08:47,260 --> 00:08:53,040 Now let's see what lesson it takes for creating objects creating copy of objects dynamically. 96 00:08:53,080 --> 00:08:55,720 So let us first create a object. 97 00:08:55,720 --> 00:09:06,350 So student history is new student and let's call betterment based constructor ages 20 and almost 200 98 00:09:08,800 --> 00:09:09,370 okay. 99 00:09:09,440 --> 00:09:11,480 Now let's bring those three 100 00:09:16,100 --> 00:09:17,220 as three add or display 101 00:09:20,960 --> 00:09:21,230 okay. 102 00:09:21,230 --> 00:09:33,180 Now let us make copies of s.t. so student as for S3 now is it right. 103 00:09:33,300 --> 00:09:35,230 Is this index right. 104 00:09:35,250 --> 00:09:36,070 No it is wrong. 105 00:09:36,070 --> 00:09:36,360 Why. 106 00:09:36,370 --> 00:09:39,980 Because Estes a pointer and I want values. 107 00:09:40,290 --> 00:09:42,530 So we have to use be defense operator. 108 00:09:43,130 --> 00:09:45,890 Now student s what is the copy of S3. 109 00:09:46,590 --> 00:10:00,450 Okay now we can create dynamic copy also how so a student is five is no student and start history. 110 00:10:00,520 --> 00:10:01,030 Okay. 111 00:10:01,190 --> 00:10:07,480 We have dos the defense operated and what if we want to create the copy of static object so the index 112 00:10:07,480 --> 00:10:19,800 will be student at 6 is no student and start to go object S1 Okay so this is how the copy constructor 113 00:10:19,800 --> 00:10:20,760 works. 114 00:10:20,760 --> 00:10:26,880 So a student S4 is the copy of S3 S5 is the copy of S3. 115 00:10:26,970 --> 00:10:31,140 Okay so we are copying the values of S3 into S5. 116 00:10:31,170 --> 00:10:36,140 Similarly the values of S1 is being copied in two S6. 117 00:10:36,360 --> 00:10:38,280 So this is all about copy constructor 118 00:10:43,750 --> 00:10:43,980 okay. 119 00:10:44,000 --> 00:10:49,430 So now we know what is a default constructor and what is a copy constructor. 120 00:10:49,460 --> 00:10:54,040 Next we do we will learn about copy assignment operator okay. 121 00:10:54,080 --> 00:10:54,460 Thank you.