get,set and value keyword in c#.net

Question

What is value keyword here and how is it assigning the value to _num? I\'m pretty confused, please give the description for the following code.

Answer 1

In the context of a property setter, the value keyword represents the value being assigned to the property. It's actually an implicit parameter of the set accessor, as if it was declared like this:

private int _num
public int num
{ 
    get 
    {
        return _num;
    }
    set(int value)
    {
        _num=value;
    }
}

Property accessors are actually methods equivalent to those:

public int get_num()
{
    return _num;
}

public void set_num(int value)
{
    _num = value;
}

Answer 2

The value keyword is a contextual keyword, that is, it has a different meaning based on its context.

Inside a set block, it simply means the value that the programmer has set it to. For instance,

className.num = 5;

In this case, value would be equal to 5 inside of the set block. So you could write:

set
{
    int temp = value; //temp = 5
    if (temp == 5) //true
    {
        //do stuff
    }
    _num = value;
}

Outside of a set block, you can use value as a variable identifier, as such:

int value = 5;

Note that you cannot do this inside a set block.

Side note: You should capitalize the property num to Num; this is a common convention that makes it easier for someone who's reading your class to identify public and private properties.

Answer 3

Properties are the way you can READ, WRITE or COMPUTE values of a private field or class variable. The set or setter inside a property is used when the code assigns a value into the private field or (class) variable. The value keyword means simply "the thing that is being assigned".

    public class StaffMember 
    { 
        private int ageValue; 
        public int Age 
            { 
                 set 
                     { 
                         if ( (value > 0) && (value < 120) ) 
                             { this.ageValue = value; } 
                     } 
                 get { 
                      return this.ageValue; 
                     } 
            } 
    }
//Rob Miles - C# Programming Yellow Book