Jos luomme kaksi tai useampia jäseniä, joilla on sama nimi, mutta eri lukumäärä tai parametrityyppi, sitä kutsutaan C++-ylikuormitukseksi. C++:ssa voimme ylikuormittaa:
- menetelmät,
- rakentajat ja
- indeksoidut ominaisuudet
Tämä johtuu siitä, että näillä jäsenillä on vain parametreja.
C++:n ylikuormitustyypit ovat:
- Toiminnan ylikuormitus
- Kuljettajan ylikuormitus
C++-toimintojen ylikuormitus
Funktioiden ylikuormitus määritellään prosessiksi, jossa on kaksi tai useampi funktio, joilla on sama nimi, mutta eri parametreilla, ja sitä kutsutaan funktion ylikuormitukseksi C++:ssa. Funktioiden ylikuormituksessa funktio määritellään uudelleen käyttämällä joko erityyppisiä argumentteja tai erilaista argumenttimäärää. Vain näiden erojen avulla kääntäjä voi erottaa toiminnot toisistaan.
tiikerin ja leijonan ero
The etu Function overloading tarkoittaa, että se lisää ohjelman luettavuutta, koska sinun ei tarvitse käyttää eri nimiä samalle toiminnolle.
Esimerkki C++-funktion ylikuormituksesta
Katsotaanpa yksinkertainen esimerkki funktion ylikuormituksesta, jossa muutamme add()-metodin argumenttien määrää.
// funktion ylikuormitusohjelma, kun argumenttien määrä vaihtelee.
#include using namespace std; class Cal { public: static int add(int a,int b){ return a + b; } static int add(int a, int b, int c) { return a + b + c; } }; int main(void) { Cal C; // class object declaration. cout<<c.add(10, 20)<<endl; cout<<c.add(12, 20, 23); return 0; } < pre> <p> <strong>Output:</strong> </p> <pre> 30 55 </pre> <p>Let's see the simple example when the type of the arguments vary.</p> <p>// Program of function overloading with different types of arguments.</p> <pre> #include using namespace std; int mul(int,int); float mul(float,int); int mul(int a,int b) { return a*b; } float mul(double x, int y) { return x*y; } int main() { int r1 = mul(6,7); float r2 = mul(0.2,3); std::cout << 'r1 is : ' <<r1<< std::endl; std::cout <<'r2 is : ' <<r2<< return 0; } < pre> <p> <strong>Output:</strong> </p> <pre> r1 is : 42 r2 is : 0.6 </pre> <h2>Function Overloading and Ambiguity</h2> <p>When the compiler is unable to decide which function is to be invoked among the overloaded function, this situation is known as <strong>function overloading</strong> .</p> <p>When the compiler shows the ambiguity error, the compiler does not run the program.</p> <p> <strong>Causes of Function Overloading:</strong> </p> <ul> <li>Type Conversion.</li> <li>Function with default arguments.</li> <li>Function with pass by reference.</li> </ul> <img src="//techcodeview.com/img/c-tutorial/89/c-overloading-function-2.webp" alt="C++ Overloading"> <ul> <li>Type Conversion:</li> </ul> <p> <strong>Let's see a simple example.</strong> </p> <pre> #include using namespace std; void fun(int); void fun(float); void fun(int i) { std::cout << 'Value of i is : ' < <i<< std::endl; } void fun(float j) { std::cout << 'value of j is : ' <<j<< int main() fun(12); fun(1.2); return 0; < pre> <p>The above example shows an error ' <strong>call of overloaded 'fun(double)' is ambiguous</strong> '. The fun(10) will call the first function. The fun(1.2) calls the second function according to our prediction. But, this does not refer to any function as in C++, all the floating point constants are treated as double not as a float. If we replace float to double, the program works. Therefore, this is a type conversion from float to double.</p> <ul> <li>Function with Default Arguments</li> </ul> <p> <strong>Let's see a simple example.</strong> </p> <pre> #include using namespace std; void fun(int); void fun(int,int); void fun(int i) { std::cout << 'Value of i is : ' < <i<< std::endl; } void fun(int a,int b="9)" { std::cout << 'value of a is : ' < <a<< <b<< int main() fun(12); return 0; pre> <p>The above example shows an error 'call of overloaded 'fun(int)' is ambiguous'. The fun(int a, int b=9) can be called in two ways: first is by calling the function with one argument, i.e., fun(12) and another way is calling the function with two arguments, i.e., fun(4,5). The fun(int i) function is invoked with one argument. Therefore, the compiler could not be able to select among fun(int i) and fun(int a,int b=9).</p> <ul> <li>Function with pass by reference</li> </ul> <p>Let's see a simple example.</p> <pre> #include using namespace std; void fun(int); void fun(int &); int main() { int a=10; fun(a); // error, which f()? return 0; } void fun(int x) { std::cout << 'Value of x is : ' <<x<< std::endl; } void fun(int &b) { std::cout << 'value of b is : ' < <b<< pre> <p>The above example shows an error ' <strong>call of overloaded 'fun(int&)' is ambiguous</strong> '. The first function takes one integer argument and the second function takes a reference parameter as an argument. In this case, the compiler does not know which function is needed by the user as there is no syntactical difference between the fun(int) and fun(int &).</p> <h2>C++ Operators Overloading</h2> <p>Operator overloading is a compile-time polymorphism in which the operator is overloaded to provide the special meaning to the user-defined data type. Operator overloading is used to overload or redefines most of the operators available in C++. It is used to perform the operation on the user-defined data type. For example, C++ provides the ability to add the variables of the user-defined data type that is applied to the built-in data types.</p> <p>The advantage of Operators overloading is to perform different operations on the same operand.</p> <p> <strong>Operator that cannot be overloaded are as follows:</strong> </p> <ul> <li>Scope operator (::)</li> <li>Sizeof</li> <li>member selector(.)</li> <li>member pointer selector(*)</li> <li>ternary operator(?:) </li> </ul> <h2>Syntax of Operator Overloading</h2> <pre> return_type class_name : : operator op(argument_list) { // body of the function. } </pre> <p>Where the <strong>return type</strong> is the type of value returned by the function. </p><p> <strong>class_name</strong> is the name of the class.</p> <p> <strong>operator op</strong> is an operator function where op is the operator being overloaded, and the operator is the keyword.</p> <h2>Rules for Operator Overloading</h2> <ul> <li>Existing operators can only be overloaded, but the new operators cannot be overloaded.</li> <li>The overloaded operator contains atleast one operand of the user-defined data type.</li> <li>We cannot use friend function to overload certain operators. However, the member function can be used to overload those operators.</li> <li>When unary operators are overloaded through a member function take no explicit arguments, but, if they are overloaded by a friend function, takes one argument.</li> <li>When binary operators are overloaded through a member function takes one explicit argument, and if they are overloaded through a friend function takes two explicit arguments. </li> </ul> <h2>C++ Operators Overloading Example</h2> <p>Let's see the simple example of operator overloading in C++. In this example, void operator ++ () operator function is defined (inside Test class).</p> <p>// program to overload the unary operator ++.</p> <pre> #include using namespace std; class Test { private: int num; public: Test(): num(8){} void operator ++() { num = num+2; } void Print() { cout<<'the count is: '<<num; } }; int main() { test tt; ++tt; calling of a function 'void operator ++()' tt.print(); return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The Count is: 10 </pre> <p>Let's see a simple example of overloading the binary operators.</p> <p>// program to overload the binary operators.</p> <pre> #include using namespace std; class A { int x; public: A(){} A(int i) { x=i; } void operator+(A); void display(); }; void A :: operator+(A a) { int m = x+a.x; cout<<'the result of the addition two objects is : '<<m; } int main() { a a1(5); a2(4); a1+a2; return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The result of the addition of two objects is : 9 </pre></'the></pre></'the></pre></x<<></pre></i<<></pre></i<<></pre></r1<<></pre></c.add(10,> Katsotaanpa yksinkertaista esimerkkiä, kun argumenttien tyyppi vaihtelee.
// Ohjelma funktion ylikuormitukseen erityyppisillä argumenteilla.
#include using namespace std; int mul(int,int); float mul(float,int); int mul(int a,int b) { return a*b; } float mul(double x, int y) { return x*y; } int main() { int r1 = mul(6,7); float r2 = mul(0.2,3); std::cout << 'r1 is : ' <<r1<< std::endl; std::cout <<\'r2 is : \' <<r2<< return 0; } < pre> <p> <strong>Output:</strong> </p> <pre> r1 is : 42 r2 is : 0.6 </pre> <h2>Function Overloading and Ambiguity</h2> <p>When the compiler is unable to decide which function is to be invoked among the overloaded function, this situation is known as <strong>function overloading</strong> .</p> <p>When the compiler shows the ambiguity error, the compiler does not run the program.</p> <p> <strong>Causes of Function Overloading:</strong> </p> <ul> <li>Type Conversion.</li> <li>Function with default arguments.</li> <li>Function with pass by reference.</li> </ul> <img src="//techcodeview.com/img/c-tutorial/89/c-overloading-function-2.webp" alt="C++ Overloading"> <ul> <li>Type Conversion:</li> </ul> <p> <strong>Let's see a simple example.</strong> </p> <pre> #include using namespace std; void fun(int); void fun(float); void fun(int i) { std::cout << 'Value of i is : ' < <i<< std::endl; } void fun(float j) { std::cout << \'value of j is : \' <<j<< int main() fun(12); fun(1.2); return 0; < pre> <p>The above example shows an error ' <strong>call of overloaded 'fun(double)' is ambiguous</strong> '. The fun(10) will call the first function. The fun(1.2) calls the second function according to our prediction. But, this does not refer to any function as in C++, all the floating point constants are treated as double not as a float. If we replace float to double, the program works. Therefore, this is a type conversion from float to double.</p> <ul> <li>Function with Default Arguments</li> </ul> <p> <strong>Let's see a simple example.</strong> </p> <pre> #include using namespace std; void fun(int); void fun(int,int); void fun(int i) { std::cout << 'Value of i is : ' < <i<< std::endl; } void fun(int a,int b="9)" { std::cout << \'value of a is : \' < <a<< <b<< int main() fun(12); return 0; pre> <p>The above example shows an error 'call of overloaded 'fun(int)' is ambiguous'. The fun(int a, int b=9) can be called in two ways: first is by calling the function with one argument, i.e., fun(12) and another way is calling the function with two arguments, i.e., fun(4,5). The fun(int i) function is invoked with one argument. Therefore, the compiler could not be able to select among fun(int i) and fun(int a,int b=9).</p> <ul> <li>Function with pass by reference</li> </ul> <p>Let's see a simple example.</p> <pre> #include using namespace std; void fun(int); void fun(int &); int main() { int a=10; fun(a); // error, which f()? return 0; } void fun(int x) { std::cout << 'Value of x is : ' <<x<< std::endl; } void fun(int &b) { std::cout << \'value of b is : \' < <b<< pre> <p>The above example shows an error ' <strong>call of overloaded 'fun(int&)' is ambiguous</strong> '. The first function takes one integer argument and the second function takes a reference parameter as an argument. In this case, the compiler does not know which function is needed by the user as there is no syntactical difference between the fun(int) and fun(int &).</p> <h2>C++ Operators Overloading</h2> <p>Operator overloading is a compile-time polymorphism in which the operator is overloaded to provide the special meaning to the user-defined data type. Operator overloading is used to overload or redefines most of the operators available in C++. It is used to perform the operation on the user-defined data type. For example, C++ provides the ability to add the variables of the user-defined data type that is applied to the built-in data types.</p> <p>The advantage of Operators overloading is to perform different operations on the same operand.</p> <p> <strong>Operator that cannot be overloaded are as follows:</strong> </p> <ul> <li>Scope operator (::)</li> <li>Sizeof</li> <li>member selector(.)</li> <li>member pointer selector(*)</li> <li>ternary operator(?:) </li> </ul> <h2>Syntax of Operator Overloading</h2> <pre> return_type class_name : : operator op(argument_list) { // body of the function. } </pre> <p>Where the <strong>return type</strong> is the type of value returned by the function. </p><p> <strong>class_name</strong> is the name of the class.</p> <p> <strong>operator op</strong> is an operator function where op is the operator being overloaded, and the operator is the keyword.</p> <h2>Rules for Operator Overloading</h2> <ul> <li>Existing operators can only be overloaded, but the new operators cannot be overloaded.</li> <li>The overloaded operator contains atleast one operand of the user-defined data type.</li> <li>We cannot use friend function to overload certain operators. However, the member function can be used to overload those operators.</li> <li>When unary operators are overloaded through a member function take no explicit arguments, but, if they are overloaded by a friend function, takes one argument.</li> <li>When binary operators are overloaded through a member function takes one explicit argument, and if they are overloaded through a friend function takes two explicit arguments. </li> </ul> <h2>C++ Operators Overloading Example</h2> <p>Let's see the simple example of operator overloading in C++. In this example, void operator ++ () operator function is defined (inside Test class).</p> <p>// program to overload the unary operator ++.</p> <pre> #include using namespace std; class Test { private: int num; public: Test(): num(8){} void operator ++() { num = num+2; } void Print() { cout<<\'the count is: \'<<num; } }; int main() { test tt; ++tt; calling of a function \'void operator ++()\' tt.print(); return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The Count is: 10 </pre> <p>Let's see a simple example of overloading the binary operators.</p> <p>// program to overload the binary operators.</p> <pre> #include using namespace std; class A { int x; public: A(){} A(int i) { x=i; } void operator+(A); void display(); }; void A :: operator+(A a) { int m = x+a.x; cout<<\'the result of the addition two objects is : \'<<m; } int main() { a a1(5); a2(4); a1+a2; return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The result of the addition of two objects is : 9 </pre></\'the></pre></\'the></pre></x<<></pre></i<<></pre></i<<></pre></r1<<> Toiminnan ylikuormitus ja epäselvyys
Kun kääntäjä ei pysty päättämään, mikä toiminto ylikuormitettujen funktioiden joukosta tulee kutsua, tämä tilanne tunnetaan nimellä toimintojen ylikuormitus .
Kun kääntäjä näyttää epäselvyysvirheen, kääntäjä ei suorita ohjelmaa.
Toiminnan ylikuormituksen syyt:
- Tyyppi muunnos.
- Funktio oletusargumenteilla.
- Toiminto viitteellä.
- Tyyppimuunnos:
Katsotaanpa yksinkertainen esimerkki.
#include using namespace std; void fun(int); void fun(float); void fun(int i) { std::cout << 'Value of i is : ' < <i<< std::endl; } void fun(float j) { std::cout << \'value of j is : \' <<j<< int main() fun(12); fun(1.2); return 0; < pre> <p>The above example shows an error ' <strong>call of overloaded 'fun(double)' is ambiguous</strong> '. The fun(10) will call the first function. The fun(1.2) calls the second function according to our prediction. But, this does not refer to any function as in C++, all the floating point constants are treated as double not as a float. If we replace float to double, the program works. Therefore, this is a type conversion from float to double.</p> <ul> <li>Function with Default Arguments</li> </ul> <p> <strong>Let's see a simple example.</strong> </p> <pre> #include using namespace std; void fun(int); void fun(int,int); void fun(int i) { std::cout << 'Value of i is : ' < <i<< std::endl; } void fun(int a,int b="9)" { std::cout << \'value of a is : \' < <a<< <b<< int main() fun(12); return 0; pre> <p>The above example shows an error 'call of overloaded 'fun(int)' is ambiguous'. The fun(int a, int b=9) can be called in two ways: first is by calling the function with one argument, i.e., fun(12) and another way is calling the function with two arguments, i.e., fun(4,5). The fun(int i) function is invoked with one argument. Therefore, the compiler could not be able to select among fun(int i) and fun(int a,int b=9).</p> <ul> <li>Function with pass by reference</li> </ul> <p>Let's see a simple example.</p> <pre> #include using namespace std; void fun(int); void fun(int &); int main() { int a=10; fun(a); // error, which f()? return 0; } void fun(int x) { std::cout << 'Value of x is : ' <<x<< std::endl; } void fun(int &b) { std::cout << \'value of b is : \' < <b<< pre> <p>The above example shows an error ' <strong>call of overloaded 'fun(int&)' is ambiguous</strong> '. The first function takes one integer argument and the second function takes a reference parameter as an argument. In this case, the compiler does not know which function is needed by the user as there is no syntactical difference between the fun(int) and fun(int &).</p> <h2>C++ Operators Overloading</h2> <p>Operator overloading is a compile-time polymorphism in which the operator is overloaded to provide the special meaning to the user-defined data type. Operator overloading is used to overload or redefines most of the operators available in C++. It is used to perform the operation on the user-defined data type. For example, C++ provides the ability to add the variables of the user-defined data type that is applied to the built-in data types.</p> <p>The advantage of Operators overloading is to perform different operations on the same operand.</p> <p> <strong>Operator that cannot be overloaded are as follows:</strong> </p> <ul> <li>Scope operator (::)</li> <li>Sizeof</li> <li>member selector(.)</li> <li>member pointer selector(*)</li> <li>ternary operator(?:) </li> </ul> <h2>Syntax of Operator Overloading</h2> <pre> return_type class_name : : operator op(argument_list) { // body of the function. } </pre> <p>Where the <strong>return type</strong> is the type of value returned by the function. </p><p> <strong>class_name</strong> is the name of the class.</p> <p> <strong>operator op</strong> is an operator function where op is the operator being overloaded, and the operator is the keyword.</p> <h2>Rules for Operator Overloading</h2> <ul> <li>Existing operators can only be overloaded, but the new operators cannot be overloaded.</li> <li>The overloaded operator contains atleast one operand of the user-defined data type.</li> <li>We cannot use friend function to overload certain operators. However, the member function can be used to overload those operators.</li> <li>When unary operators are overloaded through a member function take no explicit arguments, but, if they are overloaded by a friend function, takes one argument.</li> <li>When binary operators are overloaded through a member function takes one explicit argument, and if they are overloaded through a friend function takes two explicit arguments. </li> </ul> <h2>C++ Operators Overloading Example</h2> <p>Let's see the simple example of operator overloading in C++. In this example, void operator ++ () operator function is defined (inside Test class).</p> <p>// program to overload the unary operator ++.</p> <pre> #include using namespace std; class Test { private: int num; public: Test(): num(8){} void operator ++() { num = num+2; } void Print() { cout<<\'the count is: \'<<num; } }; int main() { test tt; ++tt; calling of a function \'void operator ++()\' tt.print(); return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The Count is: 10 </pre> <p>Let's see a simple example of overloading the binary operators.</p> <p>// program to overload the binary operators.</p> <pre> #include using namespace std; class A { int x; public: A(){} A(int i) { x=i; } void operator+(A); void display(); }; void A :: operator+(A a) { int m = x+a.x; cout<<\'the result of the addition two objects is : \'<<m; } int main() { a a1(5); a2(4); a1+a2; return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The result of the addition of two objects is : 9 </pre></\'the></pre></\'the></pre></x<<></pre></i<<></pre></i<<> Missä palautustyyppi on funktion palauttaman arvon tyyppi.
luokan nimi on luokan nimi.
operaattori op on operaattorifunktio, jossa op on ylikuormitettu operaattori ja operaattori on avainsana.
Säännöt kuljettajan ylikuormitusta varten
- Olemassa olevia operaattoreita voidaan vain ylikuormittaa, mutta uusia operaattoreita ei voi ylikuormittaa.
- Ylikuormitettu operaattori sisältää ainakin yhden käyttäjän määrittämän tietotyypin operandin.
- Emme voi käyttää ystävätoimintoa ylikuormittamaan tiettyjä operaattoreita. Jäsentoimintoa voidaan kuitenkin käyttää näiden operaattoreiden ylikuormitukseen.
- Kun unaarioperaattorit ovat ylikuormitettuja jäsenfunktion kautta, älä ota eksplisiittisiä argumentteja, mutta jos ne ovat ylikuormitettuja ystäväfunktiolla, se ottaa yhden argumentin.
- Kun binäärioperaattorit ovat ylikuormitettuja jäsenfunktion kautta, tarvitaan yksi eksplisiittinen argumentti, ja jos ne ovat ylikuormitettu ystäväfunktion kautta, tarvitaan kaksi eksplisiittistä argumenttia.
Esimerkki C++-operaattoreiden ylikuormituksesta
Katsotaanpa yksinkertainen esimerkki operaattorin ylikuormituksesta C++:ssa. Tässä esimerkissä void-operaattori ++ () -operaattorifunktio on määritelty (testiluokan sisällä).
// ohjelma ylikuormittamaan unaarioperaattoria ++.
#include using namespace std; class Test { private: int num; public: Test(): num(8){} void operator ++() { num = num+2; } void Print() { cout<<\\'the count is: \\'<<num; } }; int main() { test tt; ++tt; calling of a function \\'void operator ++()\\' tt.print(); return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The Count is: 10 </pre> <p>Let's see a simple example of overloading the binary operators.</p> <p>// program to overload the binary operators.</p> <pre> #include using namespace std; class A { int x; public: A(){} A(int i) { x=i; } void operator+(A); void display(); }; void A :: operator+(A a) { int m = x+a.x; cout<<\\'the result of the addition two objects is : \\'<<m; } int main() { a a1(5); a2(4); a1+a2; return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The result of the addition of two objects is : 9 </pre></\\'the></pre></\\'the> Katsotaanpa yksinkertainen esimerkki binäärioperaattoreiden ylikuormittamisesta.
// ohjelma ylikuormittamaan binäärioperaattoreita.
#include using namespace std; class A { int x; public: A(){} A(int i) { x=i; } void operator+(A); void display(); }; void A :: operator+(A a) { int m = x+a.x; cout<<\\'the result of the addition two objects is : \\'<<m; } int main() { a a1(5); a2(4); a1+a2; return 0; < pre> <p> <strong>Output:</strong> </p> <pre> The result of the addition of two objects is : 9 </pre></\\'the>