For a
software it’s functionality can be inbuilt by using expressions. You need to do
a lot of decision and looping for your purpose. For Example if you want to
assign values to an array you need to implement a loop and assign the values to
the corresponding elements of the array. Or if you need to take a decision you
need to check for special condition to match one of your requirements.
So here we
are going to discuss control statements and loops.
The If Statement
The if
statement evaluates an expression and branches the control . C# having there
forms of statement.
Simple If
statement
The simple
if statement takes the following form
If(Boolean
Expression)
{
// execute
statement if it is true.
}
For Eg. See
the sample
namespace
ControlStructure
{
class
Program
{
static void
Main(string[] args)
{
int a = 10;
if (a == 10)
{
Console.WriteLine("Hi
You are in a = 10");
}
}
}
}
If-Else statement
The simple
if statement is capable to evaluate your
expression if it is evaluate to true.
If you want to evaluate the expression to false and execute another statement
we can if-then-else
The format
of if else is
If(Boolean
expression
{
// execute
if it evaluate to true
}
else
{
// execute
if evaluateas false
}
For eg
namespace
ControlStructures
{
class
Program
{
static void
Main(string[] args)
{
int a = 10;
if (a == 10)
{
Console.WriteLine("Hi
You are in a = 10");
}
else
{
Console.WriteLine("Hai
you in not a != 10");
}
}
}
}
If Else IF else Statement
Some times
you need to evaluate multiple conditions conditional checking on that case you
have to use the if else statement like the following.
If(Boolean expression)
{
}else
if(Boolean expression)
{
}
….
……
Else
if(Boolean expression)
{
}
For eg.
namespace
ControlStructures
{
class
Program
{
static void
Main(string[] args)
{
int a = 10;
if (a == 10)
{
Console.WriteLine("Hi
You are in a = 10");
}
else if(a ==
20)
{Console.WriteLine("Hai
you in not a == 20");
}
else if (a
== 30)
{
Console.WriteLine("Hai
you in not a == 30");
}
}
}
}
Switch Statement
if you are
having a lot of if condition that will be same of condition then it will be a
big . In that case C# is provided with another control statement named swith. The
basic form of switch is
switch(integral
or string expression)
{
Case
<literal 1>:
Statement(s)
Break;
..
...
Case
<literal – n> :
Statement(s)
Break;
Default:
Statement
(s)
Break;
}
For Example:
namespace
args
{
int testno;
Console.Write("Enter
the no (1 - 10) for your input ");
string str =
Console.ReadLine();
testno =
Convert.ToInt32(str);
ControlStructures
{
class
Program
{
static void
Main(string[]
switch
(testno)
{
case 1:
{
Console.WriteLine(testno);
break;
}
case 2:
{
Console.WriteLine(testno);
break;
}
case 3:
{
Console.WriteLine(testno);
break;
}
case 4:
{
Console.WriteLine(testno);
break;
}
case 5:
{
Console.WriteLine(testno);
break;
}
case 6:
{
Console.WriteLine(testno);
break;
}
case 7:
{
Console.WriteLine(testno);
break;
}
case 8:
{
Console.WriteLine(testno);
break;
}
case 9:
{
Console.WriteLine(testno);
break;
}
default:
{
Console.WriteLine("wrong
entry");
break;
}
}
}
}
}
In switch it
is using of the break statement si mandatory. The switch statement can be also
be used as like as
Switch
(choice)
{
Case “exp”:
Case “exp2”:
{
// statement
Break;
}
Case “exp3”:
Case “exp4”:
{
// statement
Break;
}
}
C# loops
Lopps are
using to perform a sequence of operations in a program. In C3 we are having
four types of loops. The while loop, the
do loop, the for loop and foreach loop. Let’s see how it can be implemented.
The while
Loop
If you want
to continuesly execute a group of statements while a condition is true you can
use the while loop. It can be used on the following format.
While(Boolean
expression)
{
// statement
to be executed.
}
For eg.
class
Program
{
static void
Main(string[] args)
{
string str1
= "0";
Console.Write("Enter
Your option Y/N to continue ");
while (str1
!= "N")
{
Console.Write("Enter
The no to Display ");
str1 =
Console.ReadLine();
Console.WriteLine("You
Enetered " + str1);
}
}
}
The Do loop
The do loop
is also similar to while but sometimes you need to execute the statement at
least once. On this case you need to use the do loop. The format of do loop is
like
Do
{
}
while(Boolean
expression);
For example
class
Program
{
static void Main(string[] args)
{
string str1 = "0";
Console.WriteLine("Enter Your
option N to Exit ");
do
{
Console.Write("Enter The
no to Display ");
str1 = Console.ReadLine();
Console.WriteLine("You
Enetered " + str1);
}
while (str1 != "N");
}
}
The for Loop
The for loop
is used when you know how many times a sequence of statement is executed. The
for loop format is like
For(initialiser;Boolean
expression; modifier/increment)
{
//statements to execution.
}
class
Program
{
static void Main(string[] args)
{
for (int i = 0; i <= 10; i++)
{
Console.WriteLine("The current
value is " + i.ToString());
}
}
}
The foreach statement
The foreach statement is used when
you want to iterate through collections.
The syntax
is
Foreach(type
identifier in collection)
{
// statements
}
For eg;
class Program
{
static void Main(string[] args)
{
int[] arr = new int[10];
for (int i = 0; i<10;i++)
{
arr[i] = i;
}
foreach(int ar in arr)
{
Console.WriteLine(ar);
}
}
}
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