C#函数传参的out与ref的应用

下面我总结下我对out和ref引用参数的看法: 
1.out和ref引用参数的相同点:都是通过引用传递参数给函数; 
2.out和ref引用参数的不同点是:用ref引用传递参数,该参数必须经过初始化,并且不能在调用它的函数中初始化,以下例子是错误的： 
             namespace refConsoleApp 
             { 
              　 　class MyRefClass 
                     { 
                                 static void MyRefMethod(ref int i) 
                                { 
                                         int i=20; 
                                } 
                                static void main(string[] args) 
                                { 
                                         int value;                  //not initialized the value; 
                                         MyRefMethod(ref value); 
                                         Console.WriteLine("The value is {0}",value);  
                                } 
                       } 
             } 
3.使用out引用多个参数来返回多个值,这允许方法任意地返回需要的值，以下例子： 
namespace multi_outConsoleApp 
{ 
    class MyMultipleoutClass 
    { 
        static void MyMultipleMethod(out int i, out string str1, out string str2) 
        { 
            i = 20; 
            str1 = "I was born"; 
            str2 = "zhaoqing";

        } 
        static void Main(string[] args) 
        { 
            int value; 
            string s1, s2; 
            MyMultipleMethod(out value,out  s1,out  s2); 
            Console.WriteLine("The integer value is {0} The first string value is {1} The second string value is {2}", value, s1, s2);

        } 
    } 
}

显示的结果为： 
The integer value is 20 
The first string value is I was born 
The second string value is zhaoqing 
4.  如果一个方法使用ref引用参数,另一个方法使用out引用参数,则这两个相同方法名的函数不能重载,否则出现编译错误,以下例子出现: " cannot define overloaded  methods that differ only on ref and out " 
namespace overloadofConsoleApp 
{ 
    class overloadofclass 
    { 
        static void MyMethod(ref int i) 
        { 
            i = 20; 
        } 
        static void MyMethod(out int i) 
        { 
          i = 40; 
        } 
        static void Main(string[] args) 
        { 
            int refvalue=0; 
            MyMethod(ref refvalue); 
            Console.WriteLine("The value is {0}", refvalue); 
            int outvalue; 
            MyMethod(out outvalue); 
           Console.WriteLine("The value is {0}", outvalue); 
        } 
    } 
}   
以下例子是正确的: 
namespace overloadofConsoleApp 
{ 
    class overloadofclass 
    { 
        static void MyMethod(ref int i) 
        { 
            i = 20; 
        } 
        static void MyMethod( int i) 
        { 
          i = 40; 
        } 
        static void Main(string[] args) 
        { 
            int refvalue=0; 
            MyMethod(ref refvalue); 
            Console.WriteLine("The value is {0}", refvalue); 
            int outvalue=0; 
            MyMethod(outvalue); 
           Console.WriteLine("The value is {0}", outvalue); 
        } 
    } 
} 
显示结果为: 
The value is 20 
The value is 0 
         5.通过ref参数来改变引用类型,因为引用类型作为ref参数来传递,同时该对象会被改变.以下例子: 
namespace refConsoleApp 
{ 
    class refclass 
    { 
        static void RefMethod(ref string s) 
        { 
            s = "I was born in zhaoqing"; 
        } 
        static void Main(string[] args) 
        { 
            string str = "I am goalbell"; 
            RefMethod(ref str); 
            Console.WriteLine("The value is {0}", str); 
        } 
    } 
} 
显示结果： 
The value is I was born in zhaoqing

           6.通过ref和out来传递数组,用ref传递数组的时候，必须在main函数里面初始化一个数组，而在被调用的方法中可以指定一个数组为空值或者初始 化成一个不同的数组;用out 传递数组的时候，在被调用的方法中确定为一个数组赋值.以下例子来区别一下它们: 
namespace refszConsoleApp 
{ 
    class refszclass 
    { 
        static void RefszMethod(ref int[] arr) 
        { 
            if (arr == null)        //assigned the null value 
            { 
                arr = new int[5];   //initialized to a different array 
            } 
        } 
        static void Main(string[] args) 
        { 
            int[] theArray ={ 1, 2, 3, 4, 5 };//initialize the theArray 
            RefszMethod(ref theArray); // pass the value using of ref 
            Console.WriteLine("Array elements are:"); 
            for (int i = 0; i < theArray.Length; i++) 
            { 
                Console.WriteLine(theArray[i] + ""); 
            } 
        } 
    } 
} 
namespace outszConsoleApp 
{ 
    class outszclass 
    { 
        static void OutszMethod(out int[] arr) 
        {

            arr = new int[5] { 1, 2, 3, 4, 5 };//initialize the arr 
        } 
        static void Main(string[] args) 
        { 
            int[] theArray ; 
            OutszMethod(out theArray); 
            Console.WriteLine("Array elements are:"); 
            for (int i = 0; i < theArray.Length; i++) 
            { 
                Console.WriteLine(theArray[i] + ""); 
            } 
        } 
    } 
}