Basic data types
| C# Type |
.NET Framework type |
Size |
Range |
| bool |
System.Boolean |
2 bytes |
true / false |
| byte |
System.Byte |
Unsigned 8-bit integer |
0 to 255 |
| sbyte |
System.SByte |
Signed 8-bit integer |
-128 to 127 |
| char |
System.Char |
Unicode 16-bit character |
U+0000 to U+ffff |
| decimal |
System.Decimal |
28-29 significant digits |
±1.0 × 10−28 to ±7.9 × 1028 |
| double |
System.Double |
15-16 digits (Precision) |
±5.0 × 10−324 to ±1.7 × 10308 |
| float |
System.Single |
7 digits (Precision) |
±1.5 × 10−45 to ±3.4 × 1038 |
| int |
System.Int32 |
| -2,147,483,648 to 2,147,483,647 | |
| uint |
System.UInt32 |
Unsigned 32-bit integer |
0 to 4,294,967,295 |
| long |
System.Int64 |
Signed 64-bit integer |
–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 |
| ulong |
System.UInt64 |
Unsigned 64-bit integer |
0 to 18,446,744,073,709,551,615 |
| object |
System.Object |
assign values of any type to variables of type object. |
| short |
System.Int16 |
Signed 16-bit integer |
-32,768 to 32,767 |
|
| System.UInt16 |
Unsigned 16-bit integer |
0 to 65,535 |
| string |
System.String |
represents a string of Unicode characters. |
example :
using
System;
namespace
SyntaxCS
{
class Class1
{
[STAThread]
static void Main(string[] args)
{
int iCount; //declaring an integer variable
char cLetter; //declaring a character variable
string strName; //declaring a string variable
iCount = 10;
cLetter = 'L';
strName = "Easy Steps";
System.Console.WriteLine(iCount); //printing into the console
System.Console.WriteLine(cLetter);
System.Console.WriteLine(strName);
}
}
}
User defined data types
Class
A class is a way to bind the data and its associated functions together. It allows the data and functions to be hidden if necessary, from external use. When defining a class we are creating a new abstract data type that can be treated like any other built in type.
syntax :
[attributes] [modifiers] class [: base-list] { class-body }[;]
- attributes (Optional)
-
Additional declarative information.
- modifiers (Optional)
-
The allowed modifiers are new, abstract, sealed, and the four access modifiers.
- identifier
-
The class name.
- base-list (Optional)
-
A list that contains the one base class and any implemented interfaces, all separated by commas.
- class-body
-
Declarations of the class members.
nbsp;
example :
Using
System;
namespace
SyntaxCS
{
class Person //declaring the class
{
private int iAge;
private string strName;
public void SetDetails(int age,string name)
{
iAge = age;
strName = name;
}
public void GetDetails()
{
System.Console.WriteLine(iAge);
System.Console.WriteLine(strName);
}
}
class Class1
{
[STAThread]
static void Main(string[] args)
{
Person FirstPerson = new Person();//creating a class variable (object)
FirstPerson.SetDetails(27, "Erick");//calling a member function
FirstPerson.GetDetails();
}
}
}
Structure
A structure associates one or more members with each other and with the structure itself. When you declare a structure, it becomes a composite data type, and you can declare variables of that type.
syntax :
[ attributes] [ modifiers] struct identifier [: interfaces] body [;]
- attributes (Optional)
-
Additional declarative information.
- modifiers (Optional)
-
The allowed modifiers are new, and the four access modifiers.
-
- identifier
-
The struct name.
-
- interfaces (Optional)
- A list that contains the interfaces implemented by the struct, all separated by commas.
-
- body
- The struct body that contains member declarations.
example :
using
System;
namespace
SyntaxCS
{
struct Person //declaring the structure
{
private int iAge;
private string strName;
public void SetDetails(int age,string name)
{
iAge = age;
strName = name;
}
public void GetDetails()
{
System.Console.WriteLine(iAge);
System.Console.WriteLine(strName);
}
}
class Class1
{
[STAThread]
static void Main(string[] args)
{
Person FirstPerson = new Person();//creating a structure variable (object)
FirstPerson.SetDetails(27, "Erick");//calling a member function
FirstPerson.GetDetails();
}
}
}
Program execution control Statements
If...Then...Else Statements
An If...Then...Else statement is the basic conditional statement. If the expression in the If statement is True, the statements enclosed by the If block are executed. If the expression is False, each of the ElseIf expressions is evaluated.
syntax :
if (expression)
statement1
[else
statement2]
example :
using
System;
namespace
SyntaxCS
{
class Class1
{
[STAThread]
static void Main(string[] args)
{
int iNumber;
System.Console.WriteLine("Enter a number");
iNumber=Convert.ToInt32(System.Console.ReadLine());
if((iNumber%2)==0)
{
System.Console.WriteLine("Number is even");
}
else
{
System.Console.WriteLine("Number is odd");
}
}
}
}
Select Case
A Select Case statement executes statements based on the value of an expression.
syntax :
switch (expression)
{
case constant-expression:
statement
jump-statement
[default:
jump-statement]
}
example :
using System;
namespace
SyntaxCS
{
class Class1
{
[STAThread]
static void Main(string[] args)
{
char cLetter;
System.Console.WriteLine("Please enter a letter");
cLetter=Convert.ToChar(System.Console.ReadLine());
switch (cLetter)
{
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
System.Console.WriteLine("The letter is a Vowel");
break;
default:
System.Console.WriteLine("The letter is not a Vowel");
color=#0000ff> break;
}
}
}
}
While Do While
A While or Do loop statement loops based on a Boolean expression. A While loop statement loops as long as the Boolean expression evaluates to True;
syntax :
1) while ( )
2) do statement while ( expression);
example :
namespace SyntaxCS
{
class
Class1
{
[STAThread]
static void
Main(string[] args)
{
int x;
x = 3;
while (x < 5)
{
Console.WriteLine("while x < 5");
x += 1;
}
do
{
Console.WriteLine("Do While x > 0");
x -= 1;
}while (x > 0);
}
}
For Loop
For loop enables you to evaluate a sequence of statements multiple times.
syntax :
for ([initializers ]; [ expression]; [ iterators]) statement
example :
using
System;
namespace
SyntaxCS
{
class Class1
{
[STAThread]
static void Main(string[] args)
{
int iNumber;
for(iNumber=0;iNumber<10;iNumber++)
{
System.Console.WriteLine("VC# in Easy Steps "+(iNumber+1));
}
}
}
}
For Each Loop
A For Each...Next statement loops based on the elements in an expression. A For Each statement specifies a loop control variable and an enumerator expression.
syntax :
foreach ( type identifier in expression) statement
example :
using
System;
namespace
SyntaxCS
{
class Class1
{
[STAThread]
static void Main(string[] args)
{
int iOddCount = 0, iEvenCount = 0;
int[] iNumberarray = new int [] {0,1,2,5,7,8,11};
foreach (int itreator in iNumberarray)
{
if (itreator%2 == 0)
iEvenCount++;
else
iOddCount++;
}
Console.WriteLine("Found {0} Odd Numbers, and {1} Even Numbers.",iOddCount, iEvenCount) ;
}
}
}