Csharp/CSharp Tutorial/Class/Method Overload
Содержание
Automatic type conversions can affect overloaded method resolution: byte
<source lang="csharp">using System;
class Overload2 {
public void f(byte x) {
Console.WriteLine("Inside f(byte): " + x);
}
public void f(int x) {
Console.WriteLine("Inside f(int): " + x);
}
public void f(double x) {
Console.WriteLine("Inside f(double): " + x);
}
}
class TypeConv {
public static void Main() {
Overload2 ob = new Overload2();
int i = 10;
double d = 10.1;
byte b = 99;
short s = 10;
float f = 11.5F;
ob.f(i); // calls ob.f(int)
ob.f(d); // calls ob.f(double)
ob.f(b); // calls ob.f(byte) -- now, no type conversion
ob.f(s); // calls ob.f(int) -- type conversion
ob.f(f); // calls ob.f(double) -- type conversion
}
}</source>
Inside f(int): 10 Inside f(double): 10.1 Inside f(byte): 99 Inside f(int): 10 Inside f(double): 11.5
Automatic type conversions can affect overloaded method resolution: int, double
<source lang="csharp">using System;
class Overload2 {
public void f(int x) {
Console.WriteLine("Inside f(int): " + x);
}
public void f(double x) {
Console.WriteLine("Inside f(double): " + x);
}
}
class MainClass {
public static void Main() {
Overload2 ob = new Overload2();
int i = 10;
double d = 10.1;
byte b = 99;
short s = 10;
float f = 11.5F;
ob.f(i); // calls ob.f(int)
ob.f(d); // calls ob.f(double)
ob.f(b); // calls ob.f(int) -- type conversion
ob.f(s); // calls ob.f(int) -- type conversion
ob.f(f); // calls ob.f(double) -- type conversion
}
}</source>
Inside f(int): 10 Inside f(double): 10.1 Inside f(int): 99 Inside f(int): 10 Inside f(double): 11.5
Demonstrate method overloading: different number of parameters
<source lang="csharp">using System;
class Overload {
public void ovlDemo() {
Console.WriteLine("No parameters");
}
// Overload ovlDemo for one integer parameter.
public void ovlDemo(int a) {
Console.WriteLine("One parameter: " + a);
}
// Overload ovlDemo for two integer parameters.
public int ovlDemo(int a, int b) {
Console.WriteLine("Two parameters: " + a + " " + b);
return a + b;
}
// Overload ovlDemo for two double parameters.
public double ovlDemo(double a, double b) {
Console.WriteLine("Two double parameters: " +
a + " "+ b);
return a + b;
}
}
class MainClass {
public static void Main() {
Overload ob = new Overload();
int resI;
double resD;
// call all versions of ovlDemo()
ob.ovlDemo();
Console.WriteLine();
ob.ovlDemo(2);
Console.WriteLine();
resI = ob.ovlDemo(4, 6);
Console.WriteLine("Result of ob.ovlDemo(4, 6): " +
resI);
Console.WriteLine();
resD = ob.ovlDemo(1.1, 2.32);
Console.WriteLine("Result of ob.ovlDemo(1.1, 2.32): " +
resD);
}
}</source>
No parameters One parameter: 2 Two parameters: 4 6 Result of ob.ovlDemo(4, 6): 10 Two double parameters: 1.1 2.32 Result of ob.ovlDemo(1.1, 2.32): 3.42
Method Overloading
- In C#, two or more methods within the same class can share the same name, as long as their parameter declarations are different.
- These methods are said to be overloaded
- The process is referred to as method overloading.
- Method overloading is one of the ways to implement polymorphism.
- It is not sufficient for two methods to differ only in their return types.
- The methods must differ in the types or number of their parameters.
7.8.Method Overload 7.8.1. Method Overloading 7.8.2. <A href="/Tutorial/CSharp/0140__Class/Demonstratemethodoverloadingdifferentnumberofparameters.htm">Demonstrate method overloading: different number of parameters</a> 7.8.3. <A href="/Tutorial/CSharp/0140__Class/Automatictypeconversionscanaffectoverloadedmethodresolutionintdouble.htm">Automatic type conversions can affect overloaded method resolution: int, double</a> 7.8.4. <A href="/Tutorial/CSharp/0140__Class/Automatictypeconversionscanaffectoverloadedmethodresolutionbyte.htm">Automatic type conversions can affect overloaded method resolution: byte</a> 7.8.5. <A href="/Tutorial/CSharp/0140__Class/Overloadedconstructors.htm">Overloaded constructors</a> 7.8.6. <A href="/Tutorial/CSharp/0140__Class/Overridingamethod.htm">Overriding a method.</a>
Overloaded constructors
<source lang="csharp">public class Car {
private string make;
private string model;
private string color;
private int yearBuilt;
public Car()
{
this.make = "Ford";
this.model = "Mustang";
this.color = "red";
this.yearBuilt = 1970;
}
public Car(string make)
{
this.make = make;
this.model = "Corvette";
this.color = "silver";
this.yearBuilt = 1969;
}
public Car(string make, string model, string color, int yearBuilt)
{
this.make = make;
this.model = model;
this.color = color;
this.yearBuilt = yearBuilt;
}
public void Display()
{
System.Console.WriteLine("make = " + make);
System.Console.WriteLine("model = " + model);
System.Console.WriteLine("color = " + color);
System.Console.WriteLine("yearBuilt = " + yearBuilt);
}
} class MainClass {
public static void Main()
{
Car myCar = new Car("Toyota", "MR2", "black", 1995);
Car myCar2 = new Car();
Car myCar3 = new Car("Chevrolet");
System.Console.WriteLine("myCar details:");
myCar.Display();
System.Console.WriteLine("myCar2 details:");
myCar2.Display();
System.Console.WriteLine("myCar3 details:");
myCar3.Display();
}
}</source>
myCar details: make = Toyota model = MR2 color = black yearBuilt = 1995 myCar2 details: make = Ford model = Mustang color = red yearBuilt = 1970 myCar3 details: make = Chevrolet model = Corvette color = silver yearBuilt = 1969
Overriding a method.
<source lang="csharp">using System; public class Employee {
private int fAge;
public Employee() {
fAge = 21;
}
public virtual void setAge(int age) {
fAge = age;
}
public virtual int getAge() {
return fAge;
}
} public class AdultEmployee : Employee {
public AdultEmployee() {
}
override public void setAge(int age) {
if (age > 21)
base.setAge(age);
}
} class MainClass {
public static void Main() {
Employee p = new Employee();
p.setAge(18);
AdultEmployee ap = new AdultEmployee();
ap.setAge(18);
Console.WriteLine("Employee Age: {0}", p.getAge());
Console.WriteLine("AdultEmployee Age: {0}", ap.getAge());
}
}</source>
