This document discusses methods in object-oriented programming with C#. It defines methods as groups of statements that perform tasks and notes that every C# program has a Main method. It describes built-in methods provided by languages like Math methods and user-defined methods. It explains the syntax for defining methods, including access specifiers, return types, parameters, and bodies. It also covers passing arguments by value vs reference, and method overloading by having multiple methods with the same name but different parameters.

1. Renas R. Rekany Object-Oriented-Programming
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Programming Language with
C_Sharp
Object-Oriented-Programming
Renas R. Rekany

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Build_in and User_define C# Methods
1- Method (= Function)
A method is a group of statements that together perform a task. It combines related code together and
makes program easier. Every C# program has at least one class with a method named Main.
2- Method Types:
A. Built in: the methods that the language provides. Such as Math class provide the following
methods:
Abs (x) exp (x) tan (x)
Cos (x) pow (x,y) log (x)
Sin (x) max (x,y) Sqrt (x)
Log10, max, min, round, sqrt.
Example:
Math.abs(x);
Textbox1.text=Convert.ToString(math.abs(-10));
Math.cos(x);
B. User defines: the methods that the user defines and call.
Example:
int sum (int x , int y)
{int s=x+y;
Return (s);}
3- Defining Methods in C# and calling techniques:
When you define a method, you basically declare the elements of its structure. The syntax for
defining a method in C# is as follows:
Following are the various elements of a method:
 Access Specifier: This determines the visibility of a variable or a method from
another class.
 Return type: A method may return a value. The return type is the data type of the
value the method returns. If the method is not returning any values, then the return
type is void.
< Access Specifier> < Return Type> < Method Name> (Parameter list)
{
Body
}

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 Method name: Method name is a unique identifier and it is case sensitive. It
cannot be same as any other identifier declared in the class.
 Parameter list: Enclosed between parentheses, the parameters are used to pass
and receive data from a method. The parameter list refers to the type, order, and
number of the parameters of a method. Parameters are optional; that is, a method
may contain no parameters.
 Method body: This contains the set of instructions needed to complete the
required activity.
Example:
public void add()
{
Body
}
In the preceding example, the public is an access specifier, void is a return data type
that return nothing and add() is a method name. There is no parameter define in
add() method.
If the function returns interger value, then you can define function as follow:
public int add()
{
Body
}
If the function is returning string value, then you can define function as follow:
public string printname()
{
Body
}
You must remember, whenever use return data type with method, must return value
using return keyword from body. If you don’t want to return any value, then you can
use void data type.

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Ex:
Class program
{
public int sqr(int a)
{
return (a * a);
}
private void button1_Click(object sender, EventArgs e)
{
int b;
b =Convert.ToInt32( textBox1.Text);
textBox2.Text = Convert.ToString(sqr(b));
}
}
4- Passing arguments:
pass by value Pass by reference
static int sqr(int x)
{
return ( x * x);
} ----------
Output
- Before call x is 5
- After call x is 5
static int sqr2(ref int x)
{
return x * x;
}
----------
Output
- Before call x is 5
- After call x is 25

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5- Method overload:
A. C# enable several methods of same name to be defined in same class as long as
these method have different sets of parameters (number of parameter , type of
parameter , order of parameter ) this is called method overloaded .
B. Method overloading commonly is used to create several methods with same name
that perform similar tasks, but on different data types.
Ex:
Static int squire (int x)
{
return (x*x);
}
Static double squire (double x)
{
return (x*x);
}
static void main ( )
{
int y = 2;
double z=12.1;
textBox1.Text = Convert.ToString(squire(y));
textBox1.Text = Convert.ToString(squire(z));
}
Output
- The squire of int 2 is 4.
- The squire of double 2.1 is 4.41.
Note: This is called overload method.