C# – Type Conversion

Type conversion is converting one type of data to another type. It is also known as Type Casting. In C#, type casting has two forms −

• Implicit type conversion − These conversions are performed by C# in a type-safe manner. For example, are conversions from smaller to larger integral types and conversions from derived classes to base classes.
• Explicit type conversion − These conversions are done explicitly by users using the pre-defined functions. Explicit conversions require a cast operator.

The following example shows an explicit type conversion −

using System;

namespace TypeConversionApplication {
   class ExplicitConversion {
      static void Main(string[] args) {
         double d = 5673.74; 
         int i;
         
         // cast double to int.
         i = (int)d;
         Console.WriteLine(i);
         Console.ReadKey();
      }
   }
}

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

5673

C# Type Conversion Methods

 

Microsoft .NET provides three ways of type conversion:

1. Parsing
2. Convert Class
3. Explicit Cast Operator ()

 

Parsing

Parsing is used to convert string type data to primitive value type. For this we use parse methods with value types.

int number;

number = int.Parse(Console.ReadLine());

 

Convert Class

string num = "23";

int number = Convert.ToInt32(num);

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.

Explicit Cast Operator ()

int num1, num2;
float avg;
num1 = 10;
num2 = 21;
avg = (float)(num1 + num2) / 2;

 

 

Boxing and unboxing

Boxing and unboxing is an important concept in C# type system. With Boxing and unboxing one can link between value-types and reference-types by allowing any value of a value-type to be converted to and from type object.

Boxing

• Boxing is a mechanism in which value type is converted into reference type.
• It is implicit conversion process in which object type (super type) is used.
• In this process type and value both are stored in object type

 

Unboxing

• Unboxing is a mechanism in which reference type is converted into value.
• It is explicit conversion process.

 

Program to show boxing and unboxing:

using System;

namespace boxing
{
  class Program
  {
        static void Main(string[] args)
         {

            int i = 10;

            object o = i;             // boxing

            int j = (int)o;          // unboxing

            Console.WriteLine("value of o object : " + o);

            Console.WriteLine("Value of j : " + j);

            Console.ReadLine();

        }
    }
}