в 15:31, 26 мая 2010

2010-05-26T15:31:18Z

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2010-05-26T11:39:33Z

1 версия

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==compare the difference between passing a null reference vs. a reference to a zero length string==

<source lang="csharp">
using System;
public class Class1 {
public static void Main(string[] strings) {
Example exampleObject = new Example();
Console.WriteLine("Pass a null object:");
string s = null;
exampleObject.TestString(s);
Console.WriteLine();
Console.WriteLine("Pass an empty string:");
exampleObject.TestString("");
Console.WriteLine();
Console.WriteLine("Pass a real string:");
exampleObject.TestString("test string");
Console.WriteLine();
}
}
class Example {
public void TestString(string sTest) {
if (sTest == null) {
Console.WriteLine("sTest is null");
return;
}
if (String.rupare(sTest, "") == 0) {
Console.WriteLine("sTest references an empty string");
return;
}
Console.WriteLine("sTest refers to: "" + sTest + """);
}
}
</source>

==Reference, output and value parameters.==

<source lang="csharp">

using System;
class ReferenceAndOutputParameters
{
public void aMethod()
{
int y = 5;
int z;
Console.WriteLine( "Original value of y: {0}", y );
Console.WriteLine( "Original value of z: uninitialized\n" );
SquareRef( ref y );
SquareOut( out z );
Console.WriteLine( "Value of y after SquareRef: {0}", y );
Console.WriteLine( "Value of z after SquareOut: {0}\n", z );
Square( y );
Square( z );
Console.WriteLine( "Value of y after Square: {0}", y );
Console.WriteLine( "Value of z after Square: {0}", z );
}
void SquareRef( ref int x )
{
x = x * x;
}
void SquareOut( out int x )
{
x = 6;
x = x * x;
}
void Square( int x )
{
x = x * x;
}
}
class ReferenceAndOutputParamtersTest
{
static void Main( string[] args )
{
ReferenceAndOutputParameters test = new ReferenceAndOutputParameters();
test.aMethod();
}
}

</source>

==Testing the effects of passing array references by value and by reference.==

<source lang="csharp">

using System;
public class ArrayReferenceTest
{
public static void Main( string[] args )
{
int[] firstArray = { 1, 2, 3 };
int[] firstArrayCopy = firstArray;
for ( int i = 0; i < firstArray.Length; i++ )
Console.Write( "{0} ", firstArray[ i ] );
FirstDouble( firstArray );
for ( int i = 0; i < firstArray.Length; i++ )
Console.Write( "{0} ", firstArray[ i ] );
if ( firstArray == firstArrayCopy )
Console.WriteLine("same" );
else
Console.WriteLine("different" );
int[] secondArray = { 1, 2, 3 };
int[] secondArrayCopy = secondArray;
for ( int i = 0; i < secondArray.Length; i++ )
Console.Write( "{0} ", secondArray[ i ] );
SecondDouble( ref secondArray );
for ( int i = 0; i < secondArray.Length; i++ )
Console.Write( "{0} ", secondArray[ i ] );
if ( secondArray == secondArrayCopy )
Console.WriteLine("same" );
else
Console.WriteLine("different" );
}
public static void FirstDouble( int[] array )
{
for ( int i = 0; i < array.Length; i++ )
array[ i ] *= 2;
array = new int[] { 11, 12, 13 };
}
public static void SecondDouble( ref int[] array )
{
for ( int i = 0; i < array.Length; i++ )
array[ i ] *= 2;
array = new int[] { 11, 12, 13 };
}
}

</source>

==the out descriptor allows a function a value in an argument without initializing the argument==

<source lang="csharp">
using System;
public class Test {
public static void Main(string[] strings) {
Student student;
Example example = new Example();
example.ReturnStudent(out student);
Console.WriteLine("Student is " + student.name);
}
}
class Example {
public void ReturnStudent(out Student student) {
student = new Student();
student.name = "Jenny";
}
}
public class Student {
public string name;
}
</source>

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Csharp/C Sharp/Language Basics/Ref Out - История изменений

в 15:31, 26 мая 2010

Admin: 1 версия