What are CONST in C++ | Top and latest info 2021

CONST in C++

Today we talking all about the CONST in C++ he what it’s about people seem really confused by this so hopefully this Article will clear things up it’s a constant is more or less what I like to call a bit of a fake way because it doesn’t really do much in this car both changes Trudy generated card what it is it’s kind of like visibility for classes instructs it’s just a mechanism weekend in order to kind of make up quite a little bit clean out and full set of rules on developers working without card cost is basically sort of like a promise that you give me in which you promised that something will be constant that is it’s not going to change however it’s just a promise that you can bypass that hold promise and you can break your promise just like you can in real life like when I promise to make like daily Articles and darn yeah anyway the point is that it’s just it’s a promise you promise something to be constant and whether or not you keep that promise kind of up to you but again it’s a promise in the sense of you should be keeping that promise and the reason that we want to keep constant kind of promises is because it can actually help simplify a car lot and it has a lot of other benefits to talk about in a minute so let’s dive into some cars. CONST in C++ CONST in C++


so I can show you what I’m talking about if I declared it to judge just like this also a call to 5 on free change agents or whatever I like anyway down the road however if I do play this is a constant I cannot change it as you can see here so far running constant you’ve kind of done a few things festival Houston tactically kind of specified that any industry yeah it’s going to be a constant I’m not going to modify it this makes a lot of sense if you class something like Max H. instead of a courtroom 90 or something like that you don’t really want this to be unbearable because well it’s not very will you define the maximum age and you’re never going to change that that’s just kind of a number that you need to keep around in your program so this is probably the more simple example for how costs can be used it’s simply a way to say that I’m declaring a variable and I’m not going to. Modified bearable I don’t really want to be a variable right because the time variable implies that it can change where I. S. constant which means that you’re basically declaring a constant instead of America something that will not change now there are several uses the consulate to about them the first one applies the point is we need to clear points up sorry for now I’m going to do is credited to job however all crazy during the heat so that we actually get a point because this is the class without cost or anything I can do 2 things here the reference ID and instead of the full truth values such as terror and then of course if I print Hey. I’ll get to know as well and then the other thing. CONST in C++ CONST in C++


I can do is actually also reassign the actual points out that it points to something else like for example this Max age that I call him now to bypass this whole Constant I can cost this too and only 8 points not something you should usually enter member how I said that you can kind of break the cost promise this is one of the ways however if you try and do it in this case you can see what declared Max age as an actual constant chances are the composite cigarette trade that is kind of a return to constant pain to trying the references and actually write to it you’ll probably get a crash however for this purpose it will still work if I had it at 5 now you’ll see that I now get 90 printing because what we’ve actually done here is reassigned to point to us so we can do 2 things we can change the contents of the pointer so the contents at that memory address but then we can also change which memory address what kind of pointing to what’s now a starting cost everywhere so the first thing I can do is put costs down the front yes it’s just a constant point of what about me that means that you cannot modify the contents of that point so you can see here that I’ve created a pointer however when it’s when I’m trying to represent point to and change the value Hey you can see the icon do that the value of a being the contents at the actual memory address however reading I of course is still finding his family referencing it here printing it and when. CONST in C++ CONST in C++


I get nervous you can also an art that I’m not getting any kind of error when I try to actually change hi Sir when I change the point a to point to something else such as Max age that’s not a problem I just conscience the contents of that point Sir Dada that memory address the second way that I can use cost it by putting it off to this point of time like this what this does is kind of the opposite I can change the contents of the pointer but I con reassigned D. Axel pointer itself to point to something else if you put cost per heel right Sir basically it’s before the point I often the ins but it’s before the points up this has the exact same functionality as if I were. Right now like I did the fall like that right constant points outweigh its cons points out they mean the same thing you just be removed because but the key here is that it’s the fault the point to sign right before the asterisk where is to make the actual point of constant that we Connery assigned points up you need to put it off to the asterisk before the variable name to make sure you remember that because sometimes you will see people with different kind of programming styles running into cost pointer but just know that it’s the same as constant point up the difference is when you do in point of cost that’s the difference sorry this is not possible I constantly go to anything else like an all points or anything. CONST in C++ CONST in C++

I Congress on actually until I am but I can change the contents of what that pointer is pointing towards and finally of course I can write points twice like this which means that I cannot change the contents of the points out and I contrast axle pointer itself to point to something else so that’s kind of the second usage of consequent when you’re dealing with points as you can be talking about the pointer itself or the contents of a way the pointers pointing towards and when you put commerce here with your declaration whether it’s to the left well before the asterisk offer the asterisk as you can see it has a different meaning now lost media costs that we’re going to talk about today is to do with classes and methods of let’s run a quick cost. We will call it entity what’s going to give it CONST in C++ CONST in C++ to her Marable small house M. Y. M. X. but on a slightly different things just an example and I’m going to attempt to ride get as incentives for this now once already might get axed I’ll just make it returned thanks I’m actually going to put comments on the right side all of the method name so often after any parameters that we might be taking I’m going to write the way cost so this is kind of the third usage of it becomes kind of not really to do with terrible but after I met the name this only works in a class by the way what this means is that this this method is not going to modify any of the actual class so you can see we cannot modify class memorable. CONST in C++ CONST in C++

If I try to do something like them exceed goals through I’m not going to be able to do that right I was promised that this method is not going to modify the actual classes just kind of a redoing the method is just going to read data from the past tense lead but normally find is going to be taking place yeah so it makes sense to write cost with a gas up however with the center of course if I wanted to have a center where I set my hands down here I’m going to have to write texts so I contemplated this is cost because obviously I need to write to the class to disposes cost and typically you would declare this with a cost now of course if acts with the point time he wanted to be console around to what you could do if we just make extra points up you could do something like cost into points are constant ESCON 60. 3 and 3 times CONST in C++ CONST in C++ on that 1 line Both men how roles what this means is that we are returning a pointer they cannot be modified the contents on the point of county want to fight and this function this method promises not to modify the actual entity cost COS a lot of lot of restrictions we put on to this method let’s prevent this back to not being appointed one thing I’ll point out just quickly hop pointed out anyway one thing I’ll point out really quickly here is that by putting the points are next to the talk like on here M. S. actually become the point of it and. CONST in C++ CONST in C++

Why is this still an integer if you want everything to be appointed on one line like this you actually have to stick points next to each variable just something I thought I’d mention even though it’s a bit off topic because I’m sure people are going to be a little bit confused by that actually some rebounding back to just having a look at all the question is why would I want to declare this toughest cost like I get that I get the did it kind of promises not to touch things in this function and maybe someone else was extending that function they would say okay cool this is not meant to write to the class however it doesn’t actually feel something the answer is yes it does if we highlight how you see over here you know I’m in class let’s just write an actual practical example potentially Aram my entity and I have a function which prints my estate I want to access my ghetto so there’s something like the out we’ll have we’ll policies and see just like this for now a dog get access and we’ve got a pretty reasonable function him now I want to be able to pass this by cost reference because I don’t want to copy the ANSI class yeah we’ll talk about coping and stuff if you should be there but basically I don’t want to copy minds across because that would potentially be responding in this case it’s 8 bytes there probably wouldn’t be but in general I don’t want to copy I want to copy all my objects because that will be slow especially for something as read only follow me on the possible contracts now here’s the thing if I process by cross reference it means that this entity is cost so just like with.  CONST in C++ CONST in C++

The point is if this was a point up I can modify kind of what it’s pointing towards so I can set it all points on and that’s fine but I cannot actually modify the contents of a sort by writing contract friends like this I have the exact same cast find kennels modify the NCI Congress on it’s something else because remember this doesn’t work like it does with point is if you re assigned this reference CONST in C++ CONST in C++ you’re actually changing this object not some other object does not kind of separation between a point up and the contents of the points out because with references you on the contents right that’s all you can modify it as IT referencing you are not it’s too even though your reference and so the big thing is icon modify and C. sir if I remove this calls from this get out suddenly I’m not allowed to call back at X. function because this gas foundation does not guarantee that is not going to touch the entity he could be doing stuff like this so how does that work I’m not modifying the NC directly however I’m pulling a method the DA’s modify the empty that’s not allowed so what I have to do is modest as cost and then what that means is that when I have Michael’s entity I can call any calls to functions so because of that you actually sometimes the 2 versions of a function one which just returns tax for example with north Collins and won their tenth X. with a constant of course. CONST in C++ CONST in C++

In this case it would be using the cost version all this to get X. otherwise it will be the other one looks a bit messy with having 2 identical functions basically but that’s how it works so because of that remember to always mark your message is cost if they are actually modify the class or dental supposed to modify the cost because otherwise you would usually be stopping people from being able to use it if they have a construct friends or something like that now in some occasions you do have something that is kind of constant you really want to mock the method is cost but for some reason you just you just need it to modify some kind of terrible so supposed to be. May be had on America bearable here which we just needed to modify maybe it was something that’s just like 50 bogging off like it doesn’t really affect the program like we still want to mock the Methodist calls but we just need to touch this variable well we can do that there’s a Q. one and see what’s possible mutable cost means that it’s able to be changed so if we make this marble mutable you can see that we are modifying it even though. CONST in C++ CONST in C++

Ryan McConnell

We’re inside a cost method Ryan McConnell modified if it’s only a little bit if we market is mutable there we are we can modify it so hopefully that’s not a question answered what is readable that’s what we do is it allows functions which are constant methods which are cost to modify the terrible anyway have you guys enjoyed this Article review did you hit that like button to let me know that you enjoyed this Article if you really liked this Article you can help support the series on pantry on my going to Petra compost after January it’s a pretty cool rewards such as being able to contribute to the planning of these episodes and talk about stuff and get these upsets early sometimes as well pretty cool stuff and of course you’re helping to support the series if you have any questions about consciousness or if you feel I haven’t covered something and maybe I should if you should be you know just leave a comment below. CONST in C++ CONST in C++

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