OPERATORS IN C# .NET
The Assignment Operator
variable_name = expression;
int i=45;
The ? Operator
C/C++
contains a very powerful and convenient operator that replaces certain
statements
of the if-then-else form. The ternary operator ? takes the general form
Exp1 ? Exp2 : Exp3;
where Exp1, Exp2, and Exp3 are expressions. Notice the use and
placement of the colon.
The ? operator works like this: Exp1 is evaluated. If it is true, Exp2 is evaluated
and
becomes the value of the expression. If Exp1 is
false, Exp3 is evaluated and its
value
becomes the value of the expression. For example, in
x = 10;
y = x>9 ? 100 : 200;
y is assigned the value 100.
If x had been
less than 9, y would
have received the value
200.
The if Statement
if(condition)
{
statement
sequence
}
else
{
statement
sequence
}
The if-else-if Ladder
A common
programming construct that is based upon the nested if is the if-else-if ladder. It
looks
like this:
if(condition)
{
statement;
}
else if(condition)
{
statement;
}
else if(condition)
{
statement;
}
...
else
{
statement;
}
The switch Statement
switch()
{
case 1:
{
statement
sequence;
break;
}
case 2:
{
statement
sequence;
break;
}
case 3:
{
statement
sequence
break;
}
.
.
.
default:
statement
sequence
}
// Use
goto with a switch.
using
System;
class
SwitchGoto {
static
void Main () {
for(int
i=1; i < 5; i++) {
switch(i)
{
case 1:
Console.WriteLine("In
case 1");
goto case
3;
case 2:
Console.WriteLine("In
case 2");
goto case
1;
case 3:
Console.WriteLine("In
case 3");
goto
default;
default:
Console.WriteLine("In
default");
break;
}
Console.WriteLine();
}
One good
use for the goto is to
exit from a deeply nested routine. Here is a simple
example:
//
Demonstrate the goto.
using
System;
class
Use_goto {
static void
Main () {
int i=0,
j=0, k=0;
for(i=0;
i < 10; i++) {
for(j=0;
j < 10; j++ ) {
for(k=0;
k < 10; k++) {
Console.WriteLine("i,
j, k: " + i + " " + j + " " + k);
if(k ==
3) goto stop;
}
}
}
stop:
Console.WriteLine("Stopped!
i, j, k: " + i + ", " + j + " " + k);
}
}
Increment and Decrement
x = x +
1;
is the
same as
x++;
x +=1;
++x; //
prefix form
or as
x++; //
postfix form
and
x = x -
1;
is the
same as
x--;
x =-1;
can be
written as
- -x; //
prefix form
or as
x- -; //
postfix form
x = 10;
y = ++x;
In this
case, y will be
set to .
x = 10;
y = x++;
then y will be set to .
using System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
namespace
ConsoleApplication1
{
class Program
{
static void Main (string[] args)
{
int
x = 1;
Console.WriteLine("Series generated using y = x + ++x;");
for
(int i = 0; i < 10; i++)
{
int
y = x + x++; // prefix ++
Console.WriteLine(y
+ " ");
}
}
The
output is shown here:
Series
generated using y = x + x++;
2
4
6
8
10
12
14
16
18
20
Series
generated using y = x + ++x;
3
5
7
9
11
13
15
17
19
21
//
Compute the sum and product of the numbers from 1 to 10.
using System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
namespace
ConsoleApplication1
{
class Program
{
static void Main (string[] args)
{
int
prod;
int
sum;
int
i;
sum = 0;
prod = 1;
for
(i = 1; i <= 10; i++)
{
sum = sum + i;
prod = prod * i;
}
Console.WriteLine("Sum is " + sum);
Console.WriteLine("Product is " + prod);
}
}
}
The
output is shown here:
Sum is 55
Product
is 3628800
//
Demonstrate Math.Sin(), Math.Cos(), and Math.Tan().
using System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
namespace
ConsoleApplication1
{
class Program
{
static void Main (string[] args)
{
Double
theta; // angle in radians
for
(theta = 0.1; theta <= 1.0; theta = theta + 0.1)
{
Console.WriteLine("Sine of " + theta + " is " +
Math.Sin(theta));
Console.WriteLine("Cosine of " + theta + " is " +
Math.Cos(theta));
Console.WriteLine("Tangent of " + theta + " is " +
Math.Tan(theta));
Console.WriteLine();
}
}
}
}
Here is a
portion of the program’s output:
Sine of
0.1 is 0.0998334166468282
Cosine of
0.1 is 0.995004165278026
Tangent
of 0.1 is 0.100334672085451
Sine of
0.2 is 0.198669330795061
Cosine of
0.2 is 0.980066577841242
Tangent
of 0.2 is 0.202710035508673
Sine of
0.3 is 0.29552020666134
Cosine of
0.3 is 0.955336489125606
Tangent
of 0.3 is 0.309336249609623
using System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
namespace
ConsoleApplication1
{
class Program
{
static void Main (string[] args)
{
int
i;
Console.WriteLine("Value\tSquared\tCubed");
for(i = 1; i
< 10; i++)
Console.WriteLine("{0}\t{1}\t{2}",
i, i*i, i*i*i);
}
}
}
Value
Squared Cubed
1 1 1
2 4 8
3 9 27
4 16 64
5 25 125
6 36 216
7 49 343
8 64 512
9 81 729
//
Determine if a number is prime. If it is not, then
//
display its largest factor.
using System;
using
System.Collections.Generic;
using System.Linq;
using
System.Text;
namespace
ConsoleApplication1
{
class Program
{
static void Main (string[] args)
{
int
num;
int
i;
int
factor;
bool
isprime;
for
(num = 2; num < 20; num++)
{
isprime = true;
factor = 0;
for
(i = 2; i <= num / 2; i++)
{
if
((num % i) == 0)
{
isprime = false;
factor = i;
}
if
(isprime)
Console.WriteLine(num + " is
prime.");
else
Console.WriteLine("Largest
factor of " + num +
"
is " + factor);
}
}
}
}
}
The
output from the program is shown here:
2 is
prime.
3 is
prime.
Largest
factor of 4 is 2
5 is
prime.
Largest
factor of 6 is 3
7 is
prime.
Largest
factor of 8 is 4
Largest
factor of 9 is 3
Largest
factor of 10 is 5
11 is
prime.
Largest
factor of 12 is 6
13 is
prime.
Largest
factor of 14 is 7
Largest
factor of 15 is 5
Largest
factor of 16 is 8
17 is
prime.
Largest
factor of 18 is 9
// to get the reverse no.
using System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Text;
namespace
ConsoleApplication1
{
class Program
{
static void Main (string[] args)
{
int
num;
int
nextdigit;
num = 123;
Console.WriteLine("Number: " + num);
Console.Write("Number in reverse order: ");
do
{
nextdigit = num % 10;
num = num / 10;
} while
(num > 0);
Console.WriteLine();
}
}
}
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