help

[zhenk]

this is not hw but classwork... i wanna get a headstart since im not that great with this c++

i need to make a small program:

A) write a program that reads a positive integer and displays its factorial. the program output should look similar to:

enter an interger: 5
5! = 120

B) 0! is identified as 1 , but all negative factorial are considered to be undefined. modify the factorial program to ask the user for an integer until a positive integer or 0 is entered. the output should look similar to:\

enter an integer: -5
-5! is undefined
enter an integer 0
0! = 1

i think this program needs to use loops and im not that certain on how to use them because we just learned it and i dont really understand much but i do know a little. i tried to start it.... here is my code

Code: Select all

#include <iostream.h>

int main()

{
   int num, fact;

   cout<<endl<<"Enter an integer";
   cin>>num;

   cout<<endl<<num<<"!="<<fact;

   for(i=0; i<=n; i--)
}

[WaltP]

What is fact? I assume the factorial. Start it at 1.
You have an empty for() loop defined -- what do you think would need to go into that loop?

Use cout's within the loop to see what values are being generated as the loop ... loops

[HARiS_P]

Well if you know how to get a factorial down on paper, then it shouldn't be hard.

lets say u use 5!. That is 5!=1*2*3*4*5=120.

so you can use a loop to go from 1 to the number you want to do a factorial of. In this example 5.

and in there you can solve.

[mfrank410]

Try this...

Code: Select all

num = 5;
iFact = 0;

for ( int i = 0; i < num; i++ )
{
     iFact = (num - i) * (num -(i+1));
}


that should do it...I dont have a compiler, but basically thats one way to do it.