Integral Types
DataType
|
Size
|
.Net(CTS)
|
Comments
|
byte
|
1
|
System.Byte
|
0 - 255 It is Unsigned
|
sbyte
|
1
|
System.SByte
|
-128 to 127 - Signed
|
short
|
2
|
System.Int16
|
|
ushort
|
2
|
System.UInt16
|
|
int
|
4
|
System.Int32
|
|
uint
|
4
|
System.UInt32
|
|
long
|
8
|
System.Int64
|
|
ulong
|
8
|
System.UInt64
|
Floating Types
float
|
4
|
System.Single
|
Has up to 8 digits after decimal
|
double
|
8
|
System.Double
|
Has up to 16 digits after decimal
|
Deciaml
|
16
|
System.Decimal
|
Has fixed 28 digits after decimal and
its fixed
|
Other DataTypes
string *
|
4
|
Systring.String
|
Uses Unicode Charset
|
char
|
2
|
Systring.Char
|
Uses Unicode Charset
|
bool
|
1
|
Systring.Bool
|
|
object *
|
System.Object
|
Generic Datatype
|
Variable Declaration Syntax:
int a,b;
int a=10, b=20;
·
A local
variable declared must be explicitly initialized before used in an
expression otherwise gives an compilation error
using System;
class
Program
{
public
static void Main()
{
int n = 256;
byte b;
unchecked //Overflow checks are not done…
{
b = (byte) n;
Console.WriteLine(b);
}
checked //Overflow checks are done…
{
b = (byte) n;
Console.WriteLine(b);
}
double dbl = 0.6D;
//0.6 float f = 0.6F;
decimal dec = 0.6M;
//float and decimal requires casting dec = 10;
//Integer to decimal
//f = dec;
//Invalid //Valid in VB //dec = f;
//Invalid f = (float)
dec;
//In VB-Implicit dec = (decimal) f;
//“decimal” should be explicitly casted to every other type
if required.
string s =
"Demo";
char c = 'S';
//In VB - "S"c
//int to char. n = c;
//In VB: n = AscW(c)
/*c = n; invalid */
c = (char) n;
//In VB: c = ChrW(n)
//bool – int /anydatatype explicit or implicit casting is not
allowed either direction
//string to int s = "100";
n = (int) s;
//Invalid – String cannot be casted n = int.Parse(s);
//if failes throws, FormatException bool bln =
int.TryParse(s, out n);
//n = (int) s; //Invalid //int to string s =
n.ToString();
//s = (string) n //Invalid
//long to float - Same as VB
long lng = 10L;
f = lng;
//because range of long is smaller than float
lng = (long) f;
object obj = n; //Boxing
n = (int) obj; //Unboxing
var n = 0
// n is of type
int var s = "Hello"
// s is of type string
const double PI = 3.14;
byte b1, b2, b3;
b1 = b2 = 10;
//In VB it is not valid b1 = b2 + b3;
//Compilation Error
//if byte, short or char variables are used in an expression
they are automatically raised to the rank of int.
b1 = (byte) (b2 + b3);
Console.WriteLine(3 / 2); //Result - 1
Console.WriteLine(3.0 / 2); //Result
- 1.5
n = 10;
int m = n++;
//m=n; n=n+1
- Post Increment
Console.WriteLine(n
+ " " + m);
m = ++n;
//n=n+1; m=n - Pre Increment
Console.WriteLine(n
+ " " + m);
//?:
Conditional Operator (VB: IIf)
int max;
max = n > m ? n : m; //?: Operator
//Enum Sample
n = 2; //n is int
WeekDay wd = WeekDay.Sat;
wd = (WeekDay) n;
//Explicit
//n
= wd;
//Invalid
n = (int) wd;
//Explicit - In VB.NET it‟s not required
}
}
enum WeekDay
: int
//WeekDay is subtype of int
{
Sun=1, Mon, Tues, Wed=5, Thus, Fri, Sat
}
Enum can be
subtype of any integral type only
OverflowException.
Operators Arithmetic
|
+,
-, * , / , % (mod) (Power operator is missing)
|
Logical
Operators
|
^
(XOR), !(NOT) && (VB-AndAlso) , || (VB-OrElse)
|
Ternary
Operator
|
?:
|
String
concatenation
|
+
(VB-&)
|
Increment,
decrement
|
++
, --
|
Bitwise
|
<<
, >>, & , | , ~ (complement/negation)
|
Relational
|
=
= , != , < , > , <= , >=
|
Assignment
|
=
, += , -= , *= , /= , %= , &= , | = , ^= , <<= , >>=
|
Type
information
|
is
, sizeof , typeof, as
|
Indirection
and Address
|
*
, -> , [] , &
|
Note for VB.NET Programmers:
In C# the arithmetic operator „/
‟ is the same for both floating point and integer datatypes and the result
depends on the operands.
Control
Statements
if-statement:
if (BooleanExpression) { statement; } else if (Boolean-Expression)
{ statement; } else { statement; }
|
Switch
Statement int expr; switch (expr) //expr can only integral type /
char / string { case 0: //value of case must be a constant.
statements; goto default; // or break can be used. case 1: case 2:
statements; break; //break must be preset after every case with
statements default: statements; break; //break must be present
after default also. }
|
while…..loop
while (BooleanExpression) { Statements; }
|
do
{ Statements; }while (BooleanExpression);
|
for
and foreach statements
for
( initializer; condition; iterator )
{
statements;
}
foreach
(DataType identifier in <Array or Collection>) {
embedded-statements;
}
for (int i = 0; i < 10; i++)
{
if
(i == 7) break;
if (i == 3) continue;
Console.WriteLine(i);
}
foreach (string s in args)
Console.WriteLine(s);
|
class
Program
{
static
void Main(string[] args)
{
for
(int i = 0; i < 3; i++)
{
for
(int j = 0; j < 3; j++)
{
if
(i == j) break;
Console.WriteLine(i
+ " " + j);
}
}
}
}
|
·
“break” and “continue” statements can be used in “for”
and “while” loops.
·
C# doesn‟t
support “With” statement
Working
with Arrays
1. Single-Dimensional Arrays
int []
myArray = new int [5];
string
[]myStringArray = new string[5];
When you initialize an array upon declaration,
it is possible to use the following shortcuts:
int[] myArray = {1, 3, 5, 7, 9};
string[]
weekDays = {"Sun", "Sat", "Mon",
"Tue"};
It is
possible to declare an array variable without initialization, but you must use
the new operator when you assign an array to this variable.
For example:
int[] myArray;
myArray = new int[] {1, 3, 5, 7, 9}; // OK
myArray = {1, 3, 5, 7, 9}; // Error
weekdays = new string[] {“Sunday”, “Monday”,
“Tuesday”};
2. Multidimensional
Arrays
int[,]
myArray = new int[4,2];
Also, the
following declaration creates an array of three dimensions, 4, 2, and 3:
int[,,]
myArray = new int [4,2,3];
You can
initialize the array upon declaration as shown in the following example:
int[,] myArray = new int[,] {{1,2}, {3,4},
{5,6}, {7,8}};
You can also
initialize the array without specifying the rank:
int[,] myArray = {{1,2}, {3,4}, {5,6}, {7,8}};
If you choose to declare an array variable
without initialization, you must use the new operator to assign an array
to the variable. For example:
int[,]
myArray; myArray = new int[,] {{1,2}, {3,4}, {5,6}, {7,8}}; // OK
myArray = {{1,2}, {3,4}, {5,6}, {7,8}}; //
Error
class Program
{
static void Main(string[] args)
{
int[] ar = new int[ ] {1,2,3,4};
Console.WriteLine(ar.Length);
Console.WriteLine(ar.Rank);
//Prints Number of Dimensions in array.
foreach (int n in ar)
Console.WriteLine(n); //To
increase the size of existing array and also retaining data in it. i.e
equivalent of Redim Preserve in VB.
int[] temp =ar;
ar = new int[temp.Length +1];
Array.Copy(temp, ar, temp.Length);
temp=null;
foreach (int n in ar)
Console.WriteLine(n);
}
}
Working with Methods
using
System;
class Program2
{
public
static void Main()
{
int res = Add(10, 2);
int[] mar = { 1, 2, 3, 4 };
res = Add(mar);
res
= Add();
res = Add(1, 2, 3, 4, 5);
res = Add(1, 2, 3, 4, 5, 6);
res = Add(1, 2, 3, 4, 5, 6, 7); //Pass by
value or reference example…. int n1, n2, n3; n1 = n3 = 10;
Foo(n1,
out n2, ref n3); Console.WriteLine(n1 + " " + n2 +
" " + n3); }
//Pass by value and reference example static
void Foo(int a, out int b, ref int c)
{
a++; b = 20; c++;
}
|
static
int Add(int a, int b)
{
return
Add(a, b, 0);
}
static
int Add(int a, int b, int c)
{
return
a + b + c;
}
static
string Add(string s1, string s2)
{
return
s1 + s2;
}
static
int Add(params int[] ar)
{
int
sum = 0;
foreach
(int n in ar)
sum
+= n; return sum;
}
}
|
·
Out parameter must be
initialized in the method and are generally used in situations where we want to
return more than one value from the method.
·
C# doesn’t support Optional parameters with default
values and Named arguments.
static
int Foo(int a) { if (a != 0) return a; }
|
If
a method has return type anything other than “void”, all code paths in it must
return a value.
The
example gives compilation error because if a==0 nothing is mentioned as
return value.
|
General
Points; For String: @"C:\Demo"
or "C:\\Demo", "This is \"Quoted\" String"
