Programming

# C++ – Calculate Factorial using For, While, Do While

Write a program to calculate the factorial of an entered number using  for, while, do-while, i.        for loop,

Source Code:

```#include<iostream.h>
#include<conio.h>
void main()
{
int num,a,factorial=1;
cout<<"Enter number to find its Factorial:";
cin>>num;
for(a=1; a<=num; a++)
{
factorial=factorial*a;
}
cout<<"The Factorial of"<<num<<"="<<factorial<<endl;
getch();
}```

Output:

Enter a number to find its Factorial:5
The Factorial of5=120

ii.       do-while loop

Source Code:

```#include<iostream.h>
#include<conio.h>
void main()
{
int num, i, factorial=1;
do
{
cout<<"Enter the number:"<<endl;
cin>>num;
for(i=1; i<=num; i++)
factorial*=i;
cout<<"Factorial of"<<num<<"is:"<<factorial;
}
while(num<=2 && num>=30);
system("Pause");
getch();
}```

Output:

Enter the number:
5
Factorial of5is:120
Press any key to continue . . .

iii.     while loop.

Source Code:

```#include<iostream.h>
#include<conio.h>
void main()
{
clrscr();
int no,fact=1,i;
cout<<"Enter the no."<<endl;
cin>>no;
i=1;
while(i<=no)
{
fact=fact*i;
i++;
}
cout<<"The factorial is "<<fact;
getch();
}```

Output:

Enter the no.
5
The factorial is 120

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