# C sharp program to multiply two numbers

Example of C# program to multiply two numbers with and without user defined function. Get input from user in C# program below as number 1 and number 2, multiply two numbers and print the result.

As an example, two integer values from the user input will be taken using Console class in c# in the program and will be multiplied using the simple expression as multiplication = first *second.

Following is the output for the below programs.

Output
4
5
multiplication of 4 and 5 is 20

## C# source code example

### Method-1 using * operator

Example Program 1- multiplication of 2 numbers using * operator.

Code

`````` class Program
{
static void Main(string[] args)
{

int num1;
bool flag = false;

if (flag == false)
{
Console.WriteLine("Number 1  is a invalid number");
return;

}
flag = false;

int num2;

if (flag == false)
{
Console.WriteLine("Number 2  is a invalid number");
return;
}

int result = num1 * num2;

Console.WriteLine("multiplication of {0} and {1}  is  {2}", num1, num2, result);
}

}

``````

### Method-2 using <<,>>,& operators

Example Program 2- multiplication of 2 numbers using bitwise operators.

C# code

``````  class Multiplication
{
static void Main(string[] args)
{

int num1;
bool flag=false;

if(flag==false)
{
Console.WriteLine("Number 1  is a invalid number");
return;

}
flag=false;
int a = num1;

int num2;

if(flag==false)
{
Console.WriteLine("Number 2  is a invalid number");
return;
}
int b = num2;
int result = 0;

while(num2 !=0)
{
if ((num2 & 1) == 1)
result = result + num1;
num1 = num1 << 1; num2 = num2 >> 1;
}

Console.WriteLine("multiplication of {0} and {1}  is  {2}",a,b,result);
}
}

``````

### Method -3 using recursion

Example Program 3- multiplication of 2 numbers using recursion.

C# code

`````` class Program
{
static void Main(string[] args)
{

int num1;
bool flag = false;

if (flag == false)
{
Console.WriteLine("Number 1  is a invalid number");
return;

}
flag = false;
int a = num1;

int num2;

if (flag == false)
{
Console.WriteLine("Number 2  is a invalid number");
return;
}
int b = num2;

if(num1<num2)
{
a = num2;
b = num1;
}
Program p = new Program();
Console.WriteLine("multiplication of {0} and {1}  is  {2}", a, b, p.Multiply(a, b));
}

public int Multiply(int num1,int num2)
{
if (num2 == 0)
return 0;

return num1 + Multiply(num1, num2 - 1);
}
}
``````

Output
10
5
multiplication of 10 and 5 is 50

### Method -4 using + and – operator with loop

Example Program 4 – multiplication of 2 numbers is using + and – operator with loop.

C# code

`````` class Program
{
static void Main(string[] args)
{

int num1;
bool flag = false;

if (flag == false)
{
Console.WriteLine("Number 1  is a invalid number");
return;

}
flag = false;
int a = num1;

int num2;

if (flag == false)
{
Console.WriteLine("Number 2  is a invalid number");
return;
}
int b = num2;

if(num1<num2)
{
a = num2;
b = num1;
}

int result=0;

while(b !=0)
{
result=result+a;
b--;

}

Console.WriteLine("multiplication of {0} and {1}  is  {2}", num1, num2, result);
}

}
``````