Aren't many people using the use and as operators in C #? Don't even know?
In fact, these 2 operators are very useful in small.
1, using
As explained in MSDN
The using statement defines a scope at the end of which the object is processed.
Example:
Class Testusing:idisposable
{
public void Dispose ()
{
Console.WriteLine ("Dispose");
}
public void Method ()
{
Console.WriteLine ("Do a Method");
}
}
Call this class:
using (testusing tu=new testusing ())
{
Tu. Method ();
}
You can see the output of do a and dispose.
Note: Instantiated objects must implement the System.IDisposable interface
2, as
MSDN says:
The as operator is used to perform conversions between compatible types.
The as operator is similar to a type conversion, but when the conversion fails, the AS operator produces null instead of throwing an exception. In form, the expression of this type:
Expression as type
is equivalent to:
Expression is type? (type) expression: (type) NULL
Only expression are counted once.
Note that the AS operator only performs reference conversions and boxing conversions. The as operator cannot perform other transformations, such as user-defined conversions, which should use cast expressions instead of their execution.
Example:
Object [] arr=new object[2];
arr[0]=123;
arr[1]= "Test";
foreach (Object o in arr)
{
String s= (String) o;
Console.WriteLine (s);
}
Such code throws an exception when the conversion type fails, and the code is modified to:
Object [] arr=new object[2];
arr[0]=123;
arr[1]= "Test";
for (int i=0;i<arr. length;i++)
{
String S=arr[i] As string;
if (S!=null) Console.WriteLine (i+ ":" +s);
You can see the output is 1:test, although Arr[0] failed the conversion but did not throw an exception but returned null
Note: As must be used with reference types (int equivalence type cannot be used)
