Methods, Passing value types by value and by reference, Passing reference types by value and by reference, Passing variable number of arguments, Named arguments, Optional parameters.

1. Bhushan Mulmule
bhushan.mulmule@dotnetvideotutorial.com
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2. For video visit
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3. Methods
Passing
value types
By Value
By
Reference
Passing
reference
types
By Value
By
Reference
Agenda
Features
Variable
arguments
Named
arguments
Optional
parameters

4. Methods
 A method is a code block containing a series of statements.
 Methods are declared within a class or struct by specifying
 Access Modifier
 Other Modifiers
 Return value
 Name of the method
 Method parameters.
public static int add(int no1, int no2)
{
}
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5. Possible Combinations
• Method without parameter and no
return value
void fun1()
• Method with parameter and no return
value
void fun2(string name)
• Method with parameter and return
value
int fun3(int no1, int no2)
• Method without parameter but with
return value
string fun4()

6. Method without parameter and No return value
static void Main(string[] args)
{
greet();
Console.ReadKey();
}
static void greet()
{
Console.WriteLine("Hello");
}
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7. static void Main(string[] args)
{
greet("Mr. Anderson");
Console.ReadKey();
}
static void greet(string name)
{
Console.WriteLine("Hello " + name);
}
Method with Parameters but No Return value
Mr. Anderson
name
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8. Method With Parameters and Return value
static void Main(string[] args)
{
int no1 = 10, no2 = 20;
int result = add(no1, no2);
Console.WriteLine("Result = {0}", result);
Console.ReadKey();
}
static int add(int no1, int no2)
{
int result = no1 + no2;
return result;
}
no1
10
no2
20
no1
10
no2
20
result
30
result
30
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9. Compact Format
static void Main(string[] args)
{
Console.WriteLine(add(25,50));
}
static int add(int no1, int no2)
{
return no1 + no2;
}
no1
25
no2
50
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10. Fn without Parameter but with return value
static void Main(string[] args)
{
Console.WriteLine(GetTime());
Console.ReadKey();
}
static string GetTime()
{
string time = DateTime.Now.ToShortTimeString();
return time;
}
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11.  ref and out keyword used to pass arguments by reference
 ref: to pass references of initialized variables
 out: to pass references of uninitialized variables
 value type as well as reference type can be passed by
reference
Passing References
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12. static void Main(string[] args)
{
int no1 = 25, no2 = 50;
Console.WriteLine("Before swaping: no1 = {0}, no2 = {1}", no1, no2);
Swap(ref no1, ref no2);
Console.WriteLine("After swaping: no1 = {0}, no2 = {1}", no1, no2);
Console.ReadKey();
}
static void Swap(ref int no1,ref int no2)
{
int temp = no1;
no1 = no2;
no2 = temp;
}
ref keyword
25
no1
5420
50
no2
5424
5420
no1
5424
no2
25
temp
50 25
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13. out keyword
static void Main(string[] args)
{
float radius, area, circumference;
Console.WriteLine("Enter Radius of Circle: ");
radius = Convert.ToInt32(Console.ReadLine());
Calculate(radius, out area, out circumference);
Console.WriteLine("Area = " + area);
Console.WriteLine("Circumference = " + circumference);
}
static void Calculate(float radius, out float area, out float circumference)
{
const float pi = 3.14f;
area = 2 * pi * radius;
circumference = pi * radius * radius;
}
radius
5420
5
area
5424
circum
5428
78.5
radius
5
area
5424
circum
5428
31.4
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14. Passing Reference Types
 Reference type can be passed by value as well by reference
 If passed by value - content of object reference is passed
 If passed by reference - reference of object reference is
passed
5028
2000 5028
obj
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15. Passing string by value
static void Main(string[] args)
{
string str = "Milkyway";
Console.WriteLine("str = " + str);
ChangeString(str);
Console.WriteLine("nstr = " + str);
}
static void ChangeString(string str)
{
Console.WriteLine("nstr = " + str);
str = "Andromeda";
Console.WriteLine("nstr = " + str);
}
5028 Milkyway
Andromeda
5028
5028
6252
6252
str
str
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16. Passing string by reference
static void Main(string[] args)
{
string str = "Milkyway";
Console.WriteLine("str = " + str);
ChangeString(ref str);
Console.WriteLine("nstr = " + str);
Console.ReadKey();
}
static void ChangeString(ref string str)
{
Console.WriteLine("nstr = " + str);
str = "Andromeda";
Console.WriteLine("nstr = " + str);
}
5028 Milkyway
Andromeda
5028
6252
6252
2020
2020
str
str
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17. Passing Array by value
static void Main(string[] args)
{
int[] marks = new int[] { 10, 20, 30 };
Console.WriteLine(marks[0]);
ChangeMarks(marks);
Console.WriteLine(marks[0]);
}
static void ChangeMarks(int[] marks)
{
Console.WriteLine(marks[0]);
marks[0] = 70;
Console.WriteLine(marks[0]);
}
5028
5028
10 20 30
5028
marks
marks
70
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18. Flexibility
Variable
Arguments
Named
Arguments
Optional
Parameters

19. Passing variable number of arguments
static void Main(string[] args)
{
Console.Write("Humans : ");
printNames("Neo", "Trinity", "Morphious", "Seroph");
Console.Write("Programs : ");
printNames("Smith", "Oracle");
}
static void printNames(params string[] names)
{
foreach (string n in names)
{
Console.Write(n + " ");
}
Console.WriteLine();
}
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20. Named Arguments
static void Main(string[] args)
{
int area1 = CalculateArea(width:10,height:15);
Console.WriteLine(area1);
int area2 = CalculateArea(height: 8, width: 4);
Console.WriteLine(area2);
}
static int CalculateArea(int width, int height)
{
return width * height;
}
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21. Optional Parameters
static void Main(string[] args)
{
Score(30, 70, 60, 80);
Score(30, 70, 60);
Score(30, 70);
}
static void Score(int m1,int m2,int m3 = 50,int m4 = 30)
{
Console.WriteLine(m1 + m2 + m3 + m4);
}
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22. Bhushan Mulmule
bhushan.mulmule@dotnetvideotutorial.com
www.dotnetvideotutorial.com