About Icomparable interfece

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Please help me describe this code.

C#

public int CompareTo(object obj)
{
if (obj is Person)
{
Person otherPerson = obj as Person;
return this.Age - otherPerson.Age;
}
else
{
throw new ArgumentException(
"Object to compare to is not a Person object.");
}
}

in particular i intresting.What this two lines created for?

C#

Person otherPerson = obj as Person;
return this.Age - otherPerson.Age;

Posted 12-Dec-14 21:30pm

Inimicos

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DamithSL · Accepted Answer · 2014-12-12T21:37:00

C#

// input obj cast to Person 
Person otherPerson = obj as Person;
// return the difference of Age values of both comparing objects 
return this.Age - otherPerson.Age;

Read the documentation of IComparable Interface[^] CompareTo method should return integer value based on the comparison, here two objects are consider as in same position if the age values are equal.

OriginalGriff · Accepted Answer · 2014-12-12T21:48:00

The as operator checks the given object and if it can be converted to the given type returns it as that type. Otherwise, it returns null. It's used when you don't know what type of value is being passed into a method (often an event handler) and you need to check so that you don't cause problems by trying to use it as a type it isn't:
For example:

C#

ListBox lb = new ListBox();
...
Control c = lb;
...
TextBox tb = c as TextBox;

will give tb/code> as <code>null becasue a ListBox cannot be converted into a Textbox, whereas

C#

TextBox tb = new TextBox();
...
Control c = tb;
...
TextBox tb2 = c as TextBox;

will give tb2 as a TextBox instance.

It's a safe way of checking the type without potentially causing a type casting exception if the conversion cannot be made.

The second line subtracts two property (or field) values and returns the result to the calling method.

About Icomparable interfece

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