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Thursday, September 13, 2012

Data Type Conversion


Type Conversions


Conversion is based on type compatibility and data compatibility.

There are two types of conversions:

1.  Implicit Conversion
2.  Explicit Conversion

Implicit Conversion


In implicit conversion the compiler will make conversion for us without asking.

char -> int -> float is an example of data compatibility.

Complier checks for type compatibility at compilation.  

Practical demonstration of implicit conversion


using System;

namespace implicit_conversion
{
    class Program
    {
        static void Main(string[] args)
        {
            int num1 =20000;
            int num2 =50000;
            long total;
            // 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.
            total = num1 + num2;

            Console.WriteLine("Total is : " + total);
            Console.ReadLine();
        }
    }
}

Below table shows the implicitly type conversions that are 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 Conversion


In explicit conversion we specifically ask the compiler to convert the value into another data type.

CLR checks for data compatibility at runtime.

Explicit conversion is carried out using casts. When we cast one type to another, we deliberately force the compiler to make the transformation.

You should never expect that the cast would give you best or correct result. Casts are potentially unsafe. Casting of big data type into small may lead to loosing of data.

Practical demonstration of explicit conversion


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.

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.

Practical demonstration of parsing


using System;

namespace parsing
{
    class Program
    {
        static void Main(string[] args)
        {
            //using parsing

            int number;
            float weight;

            Console.Write("Enter any number : ");
            number = int.Parse(Console.ReadLine());

            Console.Write("Enter your weight : ");
            weight = float.Parse(Console.ReadLine());

            Console.WriteLine("You have entered : " + number);
            Console.WriteLine("You weight is : " + weight);

            Console.ReadLine();
        }
    }
}

Convert Class


One primitive type to another primitive type.

This class contains different static methods like ToInt32(), ToInt16(), ToString(), ToDateTime() etc used in type conversion.

Practical demonstration of Convert class


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();
        }
    }
}

Explicit Cast Operator ()

In general this operator is used with non-primitive types to up level or down level casting. But it can also used with any type having type compatibility and data type compatibility.

using System;

namespace explicit_cast_conversion
{
    class Program
    {
        static void Main(string[] args)
        {
            int num1, num2;
            float avg;
            num1 = 10;
            num2 = 21;
            avg = (float)(num1 + num2) / 2;

            Console.WriteLine("average is : " + avg);
            Console.ReadLine();
        }
    }
}

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