The document discusses typecasting in C#. It describes implicit and explicit typecasting. Implicit typecasting converts lower data types to higher types automatically, while explicit typecasting converts higher to lower types and requires a cast. It discusses built-in conversion methods like ToInt32() and Parse() for converting between types like string to integer. Examples are provided to demonstrate parsing strings to perform mathematical operations and converting between types.

1. C# Tutorial
Part 19:Typecasting
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2. • we can convert one datatype into different datatypes.
• it is classified into 2 types
• 1.implicit type casting
• 2.explicit type casting
• 1.implicit type casting:
• In this we convert lower datatypes are converts into higher data types.it is also called
as internal type casting. It is under control of clr;
• using System;
• namespace implicittypecastin_exm
• { class Program
• { static void Main(string[] args)
• { int i = 545454;//4 bytes
• long l = i;//8 bytes
• Console.WriteLine("the long value is:" + l.ToString());
• Console.ReadLine();
• } } }

3. • 2.Explicit type casting:
• In this we convert higher datatypes converts into lower datatypes. it is also called as
external type casting. this is under control of the programmer
• using System;
• namespace implicittypecastin_exm
• { class Program
• { static void Main(string[] args)
• { long l = 454545454;//8 bytes
• int i = l;//4 bytes
• Console.WriteLine("the int value is:" + i.ToString());
• Console.ReadLine();
• } } }
• the above example gives error. cant implicit convert higher to lower datatypes. we can
overcome this problem.explit type casting classified into

4. • 3 types :
• 1.c++ style type casting
• 2.parsing
• 3.converting
• 1.c++ style type casting:
• in this type casting higher datatypes are converts into lower datatypes.
• ex:
• long l = 454545454;//8 bytes
• int i =(int) l;//4 bytes
• Console.WriteLine("the int value is:" + i.ToString());
• Console.ReadLine();
• 2.working with parsing:
• as .net all the datatypes are predefined structures.
• int i;
• int-structure
• i-structure variable.

5. C# Type Conversion Methods
C# provides the following built-in type conversion methods:
Methods & Description
ToBoolean Converts a type to a Boolean value, where possible.
ToByte Converts a type to a byte.
ToChar Converts a type to a single Unicode character, where possible.
ToDateTime Converts a type (integer or string type) to date-time structures.
ToDecimal Converts a floating point or integer type to a decimal type.
ToDouble Converts a type to a double type.
ToInt16 Converts a type to a 16-bit integer.
ToInt32 Converts a type to a 32-bit integer.

6. ToInt64 Converts a type to a 64-bit integer.
ToSbyte Converts a type to a signed byte type.
ToSingle Converts a type to a small floating point number.
ToString Converts a type to a string.
ToType Converts a type to a specified type.
ToUInt16 Converts a type to an unsigned int type.
ToUInt32 Converts a type to an unsigned long type.
ToUInt64 Converts a type to an unsigned big integer.

7. • structure is a collection of predefined methods
• 1.minvalue()
• 2.maxvalue()
• 3.tostring()
• 4.parse()
• working with parse() is called as parsing. parse() method can be used only to convert
from strings into int. tostring() can be used only to convert from int to string.
• ex: print the limits of datatypes.
• static void Main(string[] args)
• { Console.WriteLine(byte.MinValue.ToString());
• Console.WriteLine(byte.MaxValue.ToString());
• Console.WriteLine(int.MinValue.ToString());
• Console.WriteLine(int.MaxValue.ToString());
• Console.ReadLine(); }

8. • 2.example on parsing
• 1.take the form
• 2.add 3 labels,3 textboxes,1 button control
• private void button1_Click(object sender, EventArgs e)
• { textBox3.Text = textBox1.Text + textBox2.Text; }
• o/p:1010
• it gives concatenation error
• ex:
• "10"+"10"=1010
• 10+10=20;
• we can overcome this problem using parsing method..
• textBox3.Text = (int.Parse(textBox1.Text)
+int.Parse(textBox2.Text)).ToString();

9. • 2 nd method:
• private void button1_Click(object sender, EventArgs e)
• { // textBox3.Text =
(int.Parse(textBox1.Text)
+int.Parse(textBox2.Text)).ToString();
• int a, b, c;
• a = int.Parse(textBox1.Text);
• b = int.Parse(textBox2.Text);
• c = a + b;
• textBox3.Text = c.ToString();
• }

10. • Working with converting method:
• working with convert class is called as converting.
• convert is the part fcl(frame work class library)
• convert is the collection of predefined methods
• convert.toint16()-short-2 bytes
• convert.toint32()-int-4 bytes
• convert.toint64()-long-8 bytes
• convert.tochar()
• convert.tobyte()
• convert.toboolean()
• convert.tofloat()
• convert.todouble()

11. • Example on converting:
• take the form
• 2.add 3 labels,3 textboxes,1 button control
• private void button1_Click(object sender, EventArgs e)
• { textBox3.Text = textBox1.Text + textBox2.Text; }
• o/p:1010
• it gives concatenation error
• ex:"10"+"10"=1010
• 10+10=20;
• we can overcome this problem using parsing method..
• textBox3.Text = (convert.toint32(textBox1.Text)
+convert.toint32(textBox2.Text)).ToString();

12. • 2 nd method:
• private void button1_Click(object sender, EventArgs e)
• {
• // textBox3.Text = (int.Parse(textBox1.Text)
+int.Parse(textBox2.Text)).ToString();
• int a, b, c;
• a = convert.toint16(textBox1.Text);
• b = convert.toint16(textBox2.Text);
• c = a + b;
• textBox3.Text = c.ToString();
• }

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