Flow Control (C#)

Bhushan Mulmule
bhushan.mulmule@dotnetvideotutorial.com
www.dotnetvideotutorial.com

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FlowControl
Selection
Statements
If / if – else / else if
switch - case
Loops
for
while
do while
for each
Jump Statements
goto
break
continue
Return
throw
Agenda

Selection Statements
 A selection statement causes the program control to be
transferred to a specific flow based upon whether a certain
condition is true or not.
 The following keywords are used in selection statements:
 if
 else
 switch
 case
 default

If-else
 The if statement selects a statement for execution
based on the value of a Boolean expression.
 Executes if block if condition is true and else block if
condition is false
 else block is optional

int no1, no2;
Console.Write("Enter Number1: ");
no1 = Convert.ToInt32(Console.ReadLine());
if (no1 > no2)
{
Console.WriteLine("no1 is greater than no2");
}
else
{
}
if - else
Optional

Nested if-else
 if-else can be nested either inside other if or
else block

Nested if
if (no1 > no2)
{
}
else
{
if(no1 < no2)
else
Console.WriteLine("no1 is equal to no2");
}

else-if
 else –if can be use to avoid deep nesting in case
of multiple conditions

else if
if (no1 > no2)
{
}
else if (no2 > no1)
{
}
else
{
Console.WriteLine("no1 is equal to no2");
}

switch-case
 The switch statement is a control statement that
handles multiple selections and enumerations by
passing control to one of the case statements within
its body

switch-case
int no1, no2, result = 0;
char op;
Console.Write("Enter Operator (+,-,*,/): ");
op = Convert.ToChar(Console.ReadLine());

switch (op)
{
case '+':
result = no1 + no2;
break;
case '-':
result = no1 - no2;
break;
case '*':
result = no1 * no2;
break;
case '/':
result = no1 / no2;
break;
default:
Console.WriteLine("Invalid Operator");
break;
}
Console.WriteLine("Result = " + result);
break is compulsory
default is optional

Swith-case fallthrough
 Swith-case fallthrough can be used to execute same
block for multiple cases.
 It can be achived using empty case block

Console.Write("Enter Ratings (0 to 5): ");
int ratings = Convert.ToInt32(Console.ReadLine());
switch(ratings)
{
case 0:
case 1:
Console.WriteLine("Poor");
break;
case 2:
case 3:
Console.WriteLine("Average");
break;
case 4:
Console.WriteLine("Good");
break;
}
Only empty case allow
block without break
statement
Swith-case fallthrough

Loops
 Loop executes a block of code repeatedly until a
certain condition is met.
 C# provides four loops
 for
 while
 do. . .while
 foreach

for
for (initializer; condition; iterator)
{
statement(s)
}
The initializer is the expression evaluated before the
first loop is executed
The condition is the expression checked
before each new iteration of the loop
The iterator is an expression evaluated after
each iteration

for
for (int i = 0; i < 10; i++)
{
Console.WriteLine("Hello");
}

while
int i = 0;
while(i < 10)
{
Console.WriteLine(i);
i++;
}
Initializer
Condition
Iterator

do...while
int i = 0;
do
{
Console.WriteLine("Hello " + i);
i++;
} while (i < 10);
Initializer
Condition
Iterator

foreach
int[] marks = { 50, 35, 65, 43, 65 };
foreach (int m in marks)
{
Console.WriteLine(m);
} 50 35 65 43 65
m
marks

Nested Loop
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 5; j++)
{
Console.WriteLine("i={0} j={1}",i,j);
}
Console.WriteLine();
}

Jump Statements
 Branching is performed using jump statements, which
cause an immediate transfer of the program control.
The following keywords are used in jump statements:
 break
 continue
 goto
 return
 throw

goto
static void Main(string[] args)
{
label1:
Console.WriteLine("Do you like this tutorial?");
Console.Write("Enter Y or N: ");
char response = Convert.ToChar(Console.ReadLine());
if (response == 'N' || response == 'n')
goto label1;
Console.WriteLine("O Thanks!!!");
}

break
for (int i = 0; i < 10; i++)
{
if (i == 6)
break;
Console.WriteLine("i = " + i);
}

continue
for (int i = 0; i < 10; i++)
{
if (i == 6)
continue;
Console.WriteLine("i = " + i);
}

Flow Control (C#)

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