V C++ je konstruktor posebna metoda, ki se samodejno prikliče v času ustvarjanja objekta. Na splošno se uporablja za inicializacijo podatkovnih članov novega objekta. Konstruktor v C++ ima isto ime kot razred ali struktura.
Na kratko, določen postopek, imenovan konstruktor, se samodejno pokliče, ko je objekt ustvarjen v C++. Na splošno se uporablja za ustvarjanje podatkovnih članov novih stvari. V C++ ime razreda ali strukture služi tudi kot ime konstruktorja. Ko je objekt dokončan, se pokliče konstruktor. Ker ustvarja vrednosti ali daje podatke za stvar, je znan kot konstruktor.
Prototip Constructors izgleda takole:
(list-of-parameters);
Za definiranje konstruktorja razreda se uporablja naslednja sintaksa:
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(list-of-parameters) { // constructor definition } Za definiranje konstruktorja zunaj razreda se uporablja naslednja sintaksa:
: : (list-of-parameters){ // constructor definition} Konstruktorjem manjka povratni tip, ker nimajo vrnjene vrednosti.
V C++ lahko obstajata dve vrsti konstruktorjev.
- Privzeti konstruktor
- Parametrizirani konstruktor
Privzeti konstruktor C++
Konstruktor, ki nima argumenta, je znan kot privzeti konstruktor. Prikliče se v času ustvarjanja predmeta.
Oglejmo si preprost primer privzetega konstruktorja C++.
#include using namespace std; class Employee { public: Employee() { cout<<'default constructor invoked'<<endl; } }; int main(void) { employee e1; creating an object of e2; return 0; < pre> <p> <strong>Output:</strong> </p> <pre>Default Constructor Invoked Default Constructor Invoked </pre> <h2>C++ Parameterized Constructor</h2> <p>A constructor which has parameters is called parameterized constructor. It is used to provide different values to distinct objects.</p> <p>Let's see the simple example of C++ Parameterized Constructor.</p> <pre> #include using namespace std; class Employee { public: int id;//data member (also instance variable) string name;//data member(also instance variable) float salary; Employee(int i, string n, float s) { id = i; name = n; salary = s; } void display() { cout< <id<<' '<<name<<' '<<salary<<endl; } }; int main(void) { employee e1="Employee(101," 'sonoo', 890000); creating an object of e2="Employee(102," 'nakul', 59000); e1.display(); e2.display(); return 0; < pre> <p> <strong>Output:</strong> </p> <pre>101 Sonoo 890000 102 Nakul 59000 </pre> <h2>What distinguishes constructors from a typical member function?</h2> <ol class="points"> <li>Constructor's name is the same as the class's</li> <li>Default There isn't an input argument for constructors. However, input arguments are available for copy and parameterized constructors.</li> <li>There is no return type for constructors.</li> <li>An object's constructor is invoked automatically upon creation.</li> <li>It must be shown in the classroom's open area.</li> <li>The C++ compiler creates a default constructor for the object if a constructor is not specified (expects any parameters and has an empty body).</li> </ol> <p>By using a practical example, let's learn about the various constructor types in C++. Imagine you visited a store to purchase a marker. What are your alternatives if you want to buy a marker? For the first one, you ask a store to give you a marker, given that you didn't specify the brand name or colour of the marker you wanted, simply asking for one amount to a request. So, when we just said, 'I just need a marker,' he would hand us whatever the most popular marker was in the market or his store. The default constructor is exactly what it sounds like! The second approach is to go into a store and specify that you want a red marker of the XYZ brand. He will give you that marker since you have brought up the subject. The parameters have been set in this instance thus. And a parameterized constructor is exactly what it sounds like! The third one requires you to visit a store and declare that you want a marker that looks like this (a physical marker on your hand). The shopkeeper will thus notice that marker. He will provide you with a new marker when you say all right. Therefore, make a copy of that marker. And that is what a copy constructor does!</p> <h2>What are the characteristics of a constructor?</h2> <ol class="points"> <li>The constructor has the same name as the class it belongs to.</li> <li>Although it is possible, constructors are typically declared in the class's public section. However, this is not a must.</li> <li>Because constructors don't return values, they lack a return type.</li> <li>When we create a class object, the constructor is immediately invoked.</li> <li>Overloaded constructors are possible.</li> <li>Declaring a constructor virtual is not permitted.</li> <li>One cannot inherit a constructor.</li> <li>Constructor addresses cannot be referenced to.</li> <li>When allocating memory, the constructor makes implicit calls to the new and delete operators.</li> </ol> <h2>What is a copy constructor?</h2> <p>A member function known as a copy constructor initializes an item using another object from the same class-an in-depth discussion on Copy Constructors.</p> <p>Every time we specify one or more non-default constructors (with parameters) for a class, we also need to include a default constructor (without parameters), as the compiler won't supply one in this circumstance. The best practice is to always declare a default constructor, even though it is not required.</p> <p>A reference to an object belonging to the same class is required by the copy constructor.</p> <pre> Sample(Sample &t) { id=t.id; } </pre> <h2>What is a destructor in C++?</h2> <p>An equivalent special member function to a constructor is a destructor. The constructor creates class objects, which are destroyed by the destructor. The word 'destructor,' followed by the tilde () symbol, is the same as the class name. You can only define one destructor at a time. One method of destroying an object made by a constructor is to use a destructor. Destructors cannot be overloaded as a result. Destructors don't take any arguments and don't give anything back. As soon as the item leaves the scope, it is immediately called. Destructors free up the memory used by the objects the constructor generated. Destructor reverses the process of creating things by destroying them.</p> <p>The language used to define the class's destructor</p> <pre> ~ () { } </pre> <p>The language used to define the class's destructor outside of it</p> <pre> : : ~ (){} </pre> <hr></id<<'></pre></'default> C++ parametriran konstruktor
Konstruktor, ki ima parametre, se imenuje parametrizirani konstruktor. Uporablja se za zagotavljanje različnih vrednosti različnim objektom.
Oglejmo si preprost primer C++ parametriziranega konstruktorja.
#include using namespace std; class Employee { public: int id;//data member (also instance variable) string name;//data member(also instance variable) float salary; Employee(int i, string n, float s) { id = i; name = n; salary = s; } void display() { cout< <id<<\' \'<<name<<\' \'<<salary<<endl; } }; int main(void) { employee e1="Employee(101," \'sonoo\', 890000); creating an object of e2="Employee(102," \'nakul\', 59000); e1.display(); e2.display(); return 0; < pre> <p> <strong>Output:</strong> </p> <pre>101 Sonoo 890000 102 Nakul 59000 </pre> <h2>What distinguishes constructors from a typical member function?</h2> <ol class="points"> <li>Constructor's name is the same as the class's</li> <li>Default There isn't an input argument for constructors. However, input arguments are available for copy and parameterized constructors.</li> <li>There is no return type for constructors.</li> <li>An object's constructor is invoked automatically upon creation.</li> <li>It must be shown in the classroom's open area.</li> <li>The C++ compiler creates a default constructor for the object if a constructor is not specified (expects any parameters and has an empty body).</li> </ol> <p>By using a practical example, let's learn about the various constructor types in C++. Imagine you visited a store to purchase a marker. What are your alternatives if you want to buy a marker? For the first one, you ask a store to give you a marker, given that you didn't specify the brand name or colour of the marker you wanted, simply asking for one amount to a request. So, when we just said, 'I just need a marker,' he would hand us whatever the most popular marker was in the market or his store. The default constructor is exactly what it sounds like! The second approach is to go into a store and specify that you want a red marker of the XYZ brand. He will give you that marker since you have brought up the subject. The parameters have been set in this instance thus. And a parameterized constructor is exactly what it sounds like! The third one requires you to visit a store and declare that you want a marker that looks like this (a physical marker on your hand). The shopkeeper will thus notice that marker. He will provide you with a new marker when you say all right. Therefore, make a copy of that marker. And that is what a copy constructor does!</p> <h2>What are the characteristics of a constructor?</h2> <ol class="points"> <li>The constructor has the same name as the class it belongs to.</li> <li>Although it is possible, constructors are typically declared in the class's public section. However, this is not a must.</li> <li>Because constructors don't return values, they lack a return type.</li> <li>When we create a class object, the constructor is immediately invoked.</li> <li>Overloaded constructors are possible.</li> <li>Declaring a constructor virtual is not permitted.</li> <li>One cannot inherit a constructor.</li> <li>Constructor addresses cannot be referenced to.</li> <li>When allocating memory, the constructor makes implicit calls to the new and delete operators.</li> </ol> <h2>What is a copy constructor?</h2> <p>A member function known as a copy constructor initializes an item using another object from the same class-an in-depth discussion on Copy Constructors.</p> <p>Every time we specify one or more non-default constructors (with parameters) for a class, we also need to include a default constructor (without parameters), as the compiler won't supply one in this circumstance. The best practice is to always declare a default constructor, even though it is not required.</p> <p>A reference to an object belonging to the same class is required by the copy constructor.</p> <pre> Sample(Sample &t) { id=t.id; } </pre> <h2>What is a destructor in C++?</h2> <p>An equivalent special member function to a constructor is a destructor. The constructor creates class objects, which are destroyed by the destructor. The word 'destructor,' followed by the tilde () symbol, is the same as the class name. You can only define one destructor at a time. One method of destroying an object made by a constructor is to use a destructor. Destructors cannot be overloaded as a result. Destructors don't take any arguments and don't give anything back. As soon as the item leaves the scope, it is immediately called. Destructors free up the memory used by the objects the constructor generated. Destructor reverses the process of creating things by destroying them.</p> <p>The language used to define the class's destructor</p> <pre> ~ () { } </pre> <p>The language used to define the class's destructor outside of it</p> <pre> : : ~ (){} </pre> <hr></id<<\'> Kaj razlikuje konstruktorje od tipične funkcije članice?
- Ime konstruktorja je enako kot ime razreda
- Privzeto Za konstruktorje ni vhodnega argumenta. Vendar so vhodni argumenti na voljo za kopiranje in parametrizirane konstruktorje.
- Za konstruktorje ni povratnega tipa.
- Konstruktor objekta se samodejno prikliče ob ustvarjanju.
- Prikazan mora biti na odprtem prostoru učilnice.
- Prevajalnik C++ ustvari privzeti konstruktor za objekt, če konstruktor ni določen (pričakuje vse parametre in ima prazno telo).
Na praktičnem primeru se poučimo o različnih tipih konstruktorjev v C++. Predstavljajte si, da ste obiskali trgovino, da bi kupili marker. Kakšne so vaše alternative, če želite kupiti marker? Pri prvem prosite trgovino, da vam da marker, glede na to, da niste navedli blagovne znamke ali barve želenega markerja, preprosto zahtevate en znesek na zahtevo. Torej, ko sva samo rekla: »Samo marker potrebujem,« nama je dal kateri koli marker, ki je bil najbolj priljubljen na trgu ali v njegovi trgovini. Privzeti konstruktor je točno tak, kot se sliši! Drugi pristop je, da greste v trgovino in navedete, da želite rdeči marker znamke XYZ. Dal vam bo ta marker, ker ste omenili to temo. V tem primeru so bili parametri nastavljeni tako. In parametriran konstruktor je točno to, kar se sliši! Tretji zahteva, da obiščete trgovino in izjavite, da želite marker, ki izgleda takole (fizični marker na roki). Trgovec bo tako opazil ta marker. Ko rečete, da je vse v redu, vam bo priskrbel nov marker. Zato naredite kopijo tega markerja. In to počne konstruktor kopij!
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Kakšne so značilnosti konstruktorja?
- Konstruktor ima isto ime kot razred, ki mu pripada.
- Čeprav je to mogoče, so konstruktorji običajno deklarirani v javnem razdelku razreda. Vendar to ni nujno.
- Ker konstruktorji ne vrnejo vrednosti, nimajo vrnjenega tipa.
- Ko ustvarimo objekt razreda, se takoj prikliče konstruktor.
- Možni so preobremenjeni konstruktorji.
- Razglasitev konstruktorja za navideznega ni dovoljena.
- Konstruktorja ni mogoče podedovati.
- Na naslove konstruktorja se ni mogoče sklicevati.
- Pri dodeljevanju pomnilnika konstruktor izvaja implicitne klice operatorjev new in delete.
Kaj je konstruktor kopij?
Članska funkcija, znana kot konstruktor kopiranja, inicializira element z uporabo drugega predmeta iz istega razreda - poglobljena razprava o konstruktorjih kopiranja.
Vsakič, ko podamo enega ali več neprivzetih konstruktorjev (s parametri) za razred, moramo vključiti tudi privzeti konstruktor (brez parametrov), saj ga prevajalnik v teh okoliščinah ne bo zagotovil. Najboljša praksa je, da vedno deklarirate privzeti konstruktor, čeprav ni potreben.
Referenca na objekt, ki pripada istemu razredu, zahteva konstruktor kopiranja.
Sample(Sample &t) { id=t.id; } Kaj je destruktor v C++?
Enakovredna posebna članska funkcija konstruktorju je destruktor. Konstruktor ustvari objekte razreda, ki jih destruktor uniči. Beseda 'destructor', ki ji sledi simbol tilde (), je enaka imenu razreda. Naenkrat lahko definirate samo en destruktor. Eden od načinov uničenja predmeta, ki ga je naredil konstruktor, je uporaba destruktorja. Zaradi tega destruktorjev ni mogoče preobremeniti. Destruktorji ne sprejmejo nobenih argumentov in ne vrnejo ničesar. Takoj, ko element zapusti obseg, je takoj priklican. Destruktorji sprostijo pomnilnik, ki ga uporabljajo objekti, ki jih je ustvaril konstruktor. Destructor obrne proces ustvarjanja stvari tako, da jih uniči.
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Jezik, uporabljen za definiranje destruktorja razreda
~ () { } Jezik, ki se uporablja za definiranje destruktorja razreda zunaj njega
: : ~ (){}