Hi all, in this post I will explore the concept of properties in C# this concept is same across different languages in .NET
Defn: A property is a member of a class that is used to write data into the data member and read data from the data member of a class.
A property can never store data, just used to transfer the data.
Need for properties
Consider a class
Class Employee
{
public String EmpName;
public int EmpID;
}
To use the data members of the class in another class we have to first create the object for the class and using the object we have to call the data members of the class as,
Employee obj1 = new Employee();
obj1.EmpName = CRL();
obj1.EmpID = Convert.ToInt32(CRL());
CWL(“Employee Name is s : ”obj1.EmpName);
CWL(“Employee ID is : ”obj1.EmpID);
In the above class the accessibility of the data members are public
Here in the above class the data members are public but if the data members have the accessibility as private then we cannot use obj1.EmpName or obj1.EmpID
Instead we can write the code as follows
Class Employee
{
string empName;
int empID;
public void SetEmpName(string temp)
{
EmpName = temp;
}
public string GetEmpName()
{
return EmpName;
}
public void SetEmpID(int temp)
{
EmpName = temp;
}
public int GetEmpID()
{
return EmpName;
}
}
Here we can observe that the properties are private and are accessible to outside the Employee class using the Get and Set methods.
Here the data fields are still private, only the Get and Set methods are public
In C# there is a built in mechanism to perform the above, and the mechanism is called properties
Class Employee
{
string empName;
int empID;
public string EmpName
{
set
{
EmpName = value;
}
get
{
return EmpName;
}
}
public int EmpID
{
set
{
EmpID = value;
}
get
{
return EmpID;
}
}
}
Here eventhough the data members are private we are still able to transfer the data to the data members but instead of Get and Set method we are using properties EmpName and EmpID to access the data members of the Employee class
Employee obj1 = new Employee();
//Here automatically the set assessor is called
obj1.EmpName = CRL();
obj1.EmpID = Convert.ToInt32(CRL());
//Here automatically the get assessors is being called
CWL(“Employee Name is s : ”obj1.EmpName);
CWL(“Employee ID is : ”obj1.EmpID);
Explanation
In General, Outside the class we perform the following two operations on the data fields
1) Write the data into the data member
2) Read the data from the data member
There are two assessors/methods that are available to perform this write and read operation
1) set assessor
2) get assessor
The code block for the get accessor is executed when the property is read;
The code block for the set accessor is executed when the property is assigned a new value
SET ASSESSOR
set assessor is used to write the data into the data member of a class
set assessor resembles a method whose return type is void
set assessor contains a default and fixed variable/parameter called value the type of variable is the type of the property
Whenever we call the property for writing the data then set assessor is called automatically and the data that we transfer will be stored into the value variable by default
Syntax-
set
{
datafieldname = value;
}
Example-
set
{
empID = value;
}
GET ASSESSOR
get assessor is used to read the data from the data member of the class
Whenever we call the property for reading the data get assessor is called automatically and will return the data field data
Syntax-
get
{
return datafieldname;
}
Example-
get
{
return empID;
}
Types of properties
C#.NET supports three types of propertied
1) Read only property
2) Write only property
3) Read Write property
READ ONLY PROPERTY
A Read only property is used to read the data from the data field
We cannot write the data using read only property
This property contains only one assessor i.e. get assessor
Sytnax-
AccessModifier DataType PropertyName
{
get
{
return datafieldname;
}
}
Example-
public int EmpID
{
get
{
return empID;
}
}
WRITE ONLY PROPERTY
A Write only property is used only to write the data into the data field
We cannot read the data using write only property
This property contains only one assessor i.e. set assessor
Sytnax-
AccessModifier DataType PropertyName
{
set
{
datafieldname =value;
}
}
Example-
public void EmpID
{
set
{
empID = value;
}
}
READ WRITE PROPERTY
A Read Write property is used to perform both read and write operation
This property contains both get and set assessor
Sytnax-
AccessModifier DataType PropertyName
{
set
{
datafieldname =value;
}
get
{
return datafieldname;
}
}
Example-
public void EmpID
{
set
{
empID = value;
}
get
{
return empID;
}
}
Advantages of properties
1)Properties provide a layer of abstraction
(we can have different property name from the data field name)
2)Properties provide security to the data fields
(we can make a data meber read only thus providing the security)
3)Properites can be used to validate data before reading and writing operations.
Example -
set
if ((value > 0) && (value< 13))
{
month = value;
}
Here if the data is stored only if the value is between 1 to 12
get
{
return name == null ? "NA" : name ;
}
Here if name has null then NA is returned.
-
Further Reading
http://msdn.microsoft.com/en-us/library/w86s7x04%28v=vs.100%29.aspx
Defn: A property is a member of a class that is used to write data into the data member and read data from the data member of a class.
A property can never store data, just used to transfer the data.
Need for properties
Consider a class
Class Employee
{
public String EmpName;
public int EmpID;
}
To use the data members of the class in another class we have to first create the object for the class and using the object we have to call the data members of the class as,
Employee obj1 = new Employee();
obj1.EmpName = CRL();
obj1.EmpID = Convert.ToInt32(CRL());
CWL(“Employee Name is s : ”obj1.EmpName);
CWL(“Employee ID is : ”obj1.EmpID);
In the above class the accessibility of the data members are public
Here in the above class the data members are public but if the data members have the accessibility as private then we cannot use obj1.EmpName or obj1.EmpID
Instead we can write the code as follows
Class Employee
{
string empName;
int empID;
public void SetEmpName(string temp)
{
EmpName = temp;
}
public string GetEmpName()
{
return EmpName;
}
public void SetEmpID(int temp)
{
EmpName = temp;
}
public int GetEmpID()
{
return EmpName;
}
}
Here we can observe that the properties are private and are accessible to outside the Employee class using the Get and Set methods.
Here the data fields are still private, only the Get and Set methods are public
In C# there is a built in mechanism to perform the above, and the mechanism is called properties
Class Employee
{
string empName;
int empID;
public string EmpName
{
set
{
EmpName = value;
}
get
{
return EmpName;
}
}
public int EmpID
{
set
{
EmpID = value;
}
get
{
return EmpID;
}
}
}
Here eventhough the data members are private we are still able to transfer the data to the data members but instead of Get and Set method we are using properties EmpName and EmpID to access the data members of the Employee class
Employee obj1 = new Employee();
//Here automatically the set assessor is called
obj1.EmpName = CRL();
obj1.EmpID = Convert.ToInt32(CRL());
//Here automatically the get assessors is being called
CWL(“Employee Name is s : ”obj1.EmpName);
CWL(“Employee ID is : ”obj1.EmpID);
Explanation
In General, Outside the class we perform the following two operations on the data fields
1) Write the data into the data member
2) Read the data from the data member
There are two assessors/methods that are available to perform this write and read operation
1) set assessor
2) get assessor
The code block for the get accessor is executed when the property is read;
The code block for the set accessor is executed when the property is assigned a new value
SET ASSESSOR
set assessor is used to write the data into the data member of a class
set assessor resembles a method whose return type is void
set assessor contains a default and fixed variable/parameter called value the type of variable is the type of the property
Whenever we call the property for writing the data then set assessor is called automatically and the data that we transfer will be stored into the value variable by default
Syntax-
set
{
datafieldname = value;
}
Example-
set
{
empID = value;
}
GET ASSESSOR
get assessor is used to read the data from the data member of the class
Whenever we call the property for reading the data get assessor is called automatically and will return the data field data
Syntax-
get
{
return datafieldname;
}
Example-
get
{
return empID;
}
Types of properties
C#.NET supports three types of propertied
1) Read only property
2) Write only property
3) Read Write property
READ ONLY PROPERTY
A Read only property is used to read the data from the data field
We cannot write the data using read only property
This property contains only one assessor i.e. get assessor
Sytnax-
AccessModifier DataType PropertyName
{
get
{
return datafieldname;
}
}
Example-
public int EmpID
{
get
{
return empID;
}
}
WRITE ONLY PROPERTY
A Write only property is used only to write the data into the data field
We cannot read the data using write only property
This property contains only one assessor i.e. set assessor
Sytnax-
AccessModifier DataType PropertyName
{
set
{
datafieldname =value;
}
}
Example-
public void EmpID
{
set
{
empID = value;
}
}
READ WRITE PROPERTY
A Read Write property is used to perform both read and write operation
This property contains both get and set assessor
Sytnax-
AccessModifier DataType PropertyName
{
set
{
datafieldname =value;
}
get
{
return datafieldname;
}
}
Example-
public void EmpID
{
set
{
empID = value;
}
get
{
return empID;
}
}
Advantages of properties
1)Properties provide a layer of abstraction
(we can have different property name from the data field name)
2)Properties provide security to the data fields
(we can make a data meber read only thus providing the security)
3)Properites can be used to validate data before reading and writing operations.
Example -
set
if ((value > 0) && (value< 13))
{
month = value;
}
Here if the data is stored only if the value is between 1 to 12
get
{
return name == null ? "NA" : name ;
}
Here if name has null then NA is returned.
-
Further Reading
http://msdn.microsoft.com/en-us/library/w86s7x04%28v=vs.100%29.aspx
