C Sharp Type Conversion or Type Casting

Converting one type of data into another data type is  known as Type Conversion or Type Casting. System.Convert class provides a complete set of methods for supported conversions.They are two types:

(i)implicit type conversion   (ii) Explicit type conversion

• Implicit type conversion - These conversions are performed automatically by the compiler and no data will be lost. For example  conversion of a smaller data type to a larger data types and conversion of derived classes to base class. This is a safe type conversion.Example :

using System;

 

namespace implicit_conversion

{

    class Program

    {

        static void Main(string[] args)

        {

            int num1 =30000;

            int num2 =50000;

            long sum;

            // In this the int values are implicitly converted to long data type;

            //you need not to tell compiler to do the conversion, it automatically does.

            sum = num1 + num2;

 

            Console.WriteLine("Sum is : " +sum);

            Console.ReadLine();

        }

    }

}

Implicitly type conversionstable  supported by C#:

 

From	To
sbyte	short, int, long, float, double, decimal
byte	short, ushort, int, uint, long, ulong, float, double, decimal
short	int, long, float, double, decimal
ushort	int, uint, long, ulong, float, double, decimal
int	long, float, double, decimal
uint	long, ulong, float, double, decimal
long	float, double, decimal
ulong	float, double, decimal
float	double
char	ushort, int, uint, long, ulong, float, double, decimal

• Explicit type conversion - These conversions are done explicitly by users using the pre-defined functions. Explicit conversions require a cast operator. For example conversion of larger data type to smaller data type and conversion of base class to derived classes. In this conversion information might be lost or conversion might not be succeed for some reasons. This is an un-safe type conversion.

Explicit type conversion:

Ex-1:

using System;

namespace TypeConversionApplication

{

   class ExplicitConversion

   {

      static void Main(string[] args)

      {

         double d = 6313.74;

         int i;

        

         // cast double to int.

         i = (int)d;

         Console.WriteLine(i);

         Console.ReadKey();

      }

   }

}

OUTPUT: 6313                

Ex-2:

using System;

 

namespace explicit_conversion

{

    class Program

    {

        static void Main(string[] args)

        {

            int num = 65;

           

            char alpha;

            alpha = (char)num;

            // In this the int values are explicitly converted to char data type;

            //you have to tell compiler to do the conversion, it uses casting.

           

            Console.WriteLine("alphabet is: " + alpha);

            Console.ReadLine();

        }

    }

}

 

Note: You can also use Explicit Cast Operator () and unboxing for explicit conversion.

C# Type Conversion Methods

C# provides the following built-in type conversion methods:

Sr.No	Methods & Description
1	ToBoolean Converts a type to a Boolean value, where possible.
2	ToByte Converts a type to a byte.
3	ToChar Converts a type to a single Unicode character, where possible.
4	ToDateTime Converts a type (integer or string type) to date-time structures.
5	ToDecimal Converts a floating point or integer type to a decimal type.
6	ToDouble Converts a type to a double type.
7	ToInt16 Converts a type to a 16-bit integer.
8	ToInt32 Converts a type to a 32-bit integer.
9	ToInt64 Converts a type to a 64-bit integer.
10	ToSbyte Converts a type to a signed byte type.
11	ToSingle Converts a type to a small floating point number.
12	ToString Converts a type to a string.
13	ToType Converts a type to a specified type.
14	ToUInt16 Converts a type to an unsigned int type.
15	ToUInt32 Converts a type to an unsigned long type.
16	ToUInt64 Converts a type to an unsigned big integer.

The following example is on conversin using conversion methods that converts value types into string types:

Ex-1

using System;

namespace TypeConversionApplication

{

   class StringConversion

   {

      static void Main(string[] args)

      {

         int i = 75;

         float f = 53.005f;

         double d = 2345.7652;

         bool b = true;

         Console.WriteLine(i.ToString());

         Console.WriteLine(f.ToString());

         Console.WriteLine(d.ToString());

         Console.WriteLine(b.ToString());

         Console.ReadKey();

           

      }

   }

}

When the above code is compiled and executed, it produces the following result:

75

53.005

2345.7652

True

Ex-2

using System;

 

namespace convert_conversion

{

    class Program

    {

        static void Main(string[] args)

        {

            // example of using convert class

 

            string num = "23";

            int number = Convert.ToInt32(num);

 

            int age = 24;

            string vote = Convert.ToString(age);

 

            Console.WriteLine("Your number is : " + number);

            Console.WriteLine("Your voting age is : " + age);

 

            Console.ReadLine();

        }

    }

}

Note:  Upcasting and Downcasting?

Implicit conversion of derived classes to base class is called Upcasting and Explicit conversion of base class to derived classes is called Downcasting.