return
語句可用於從函式中返回一個值。 但是,使用輸出引數,可以從函式返回兩個值。輸出引數與參照引數相似,不同之處在於它們將資料從方法中傳輸出去,而不是傳入其中。
以下範例說明了這一點:
using System;
namespace CalculatorApplication
{
class NumberManipulator
{
public void getValue(out int x )
{
int temp = 5;
x = temp;
}
static void Main(string[] args)
{
NumberManipulator n = new NumberManipulator();
/* local variable definition */
int a = 100;
Console.WriteLine("Before method call, value of a : {0}", a);
/* calling a function to get the value */
n.getValue(out a);
Console.WriteLine("After method call, value of a : {0}", a);
Console.ReadLine();
}
}
}
當編譯和執行上述程式碼時,會產生以下結果:
Before method call, value of a : 100
After method call, value of a : 5
為輸出引數提供的變數不需要分配值。當需要通過引數返回值時,輸出引數特別有用,而無需為引數分配初始值。參考以下範例來了解:
using System;
namespace CalculatorApplication
{
class NumberManipulator
{
public void getValues(out int x, out int y )
{
Console.WriteLine("Enter the first value: ");
x = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Enter the second value: ");
y = Convert.ToInt32(Console.ReadLine());
}
static void Main(string[] args)
{
NumberManipulator n = new NumberManipulator();
/* local variable definition */
int a , b;
/* calling a function to get the values */
n.getValues(out a, out b);
Console.WriteLine("After method call, value of a : {0}", a);
Console.WriteLine("After method call, value of b : {0}", b);
Console.ReadLine();
}
}
}
當編譯和執行上述程式碼時,會產生以下結果:
Enter the first value:
17
Enter the second value:
19
After method call, value of a : 17
After method call, value of b : 19