Re: [Dev-C++] factorial code additional

[Daniel G. <sp...@ho...>]

<html><div style='background-color:'><DIV>
<P>Here's what I ended up doing.</P>
<P>&nbsp;</P>
<P>#include &lt;stdio.h&gt;</P>
<P>int main()</P>
<P>{<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int a,b,c;</P>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; printf("Input number");</P>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; scanf("%d",&amp;a); /*&nbsp; %d is for an int I think in C. &amp;a assigns that value to a */<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;c = a-1;<BR>&nbsp;&nbsp;b = a*c;<BR>&nbsp;&nbsp;c--;<BR>&nbsp;&nbsp;while (c &gt;= 1) </P>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp; b = b*c--;<BR>&nbsp;&nbsp;&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; printf ("The factoral of %d is %d\n", a, b );<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return 0;<BR>}</P>
<P><BR><BR><BR>But thanks, I'll look over yours :)</P></DIV>
<DIV></DIV>
<DIV></DIV>&gt;From: "Jason Hardman" <JAS...@BT...>
<DIV></DIV>&gt;To: "Daniel Glenfield" <SP...@HO...>
<DIV></DIV>&gt;Subject: Re: [Dev-C++] factorial code additional 
<DIV></DIV>&gt;Date: Mon, 22 Oct 2001 00:05:51 +0100 
<DIV></DIV>&gt; 
<DIV></DIV>&gt;I'm not sure what you mean about it having 3 variables, but here is a version that works. Note that I have created a factorial function. I'm not entirly sure what you were doing in your version, but you forgot to store the variables you were working with, and didn't initialse b to anything. If you perform a calculation you have to assign it's result to something. 
<DIV></DIV>&gt; 
<DIV></DIV>&gt;#include <CSTDLIB>
<DIV></DIV>&gt;#include <CSTDIO>
<DIV></DIV>&gt; 
<DIV></DIV>&gt;inline int factorial(int n); 
<DIV></DIV>&gt; 
<DIV></DIV>&gt;int main(int argc, char *argv[]) 
<DIV></DIV>&gt;{ 
<DIV></DIV>&gt; int a, b; 
<DIV></DIV>&gt; printf("Input number: "); 
<DIV></DIV>&gt; scanf("%d", &amp;a); 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; // calculate factorial here 
<DIV></DIV>&gt; b = factorial(a); 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; printf("The factoral of %d is %d\n", a, b); 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; system("PAUSE"); 
<DIV></DIV>&gt; return 0; 
<DIV></DIV>&gt;} 
<DIV></DIV>&gt; 
<DIV></DIV>&gt;// factorial function 
<DIV></DIV>&gt;inline int factorial(int n) 
<DIV></DIV>&gt;{ 
<DIV></DIV>&gt; int r = 1; 
<DIV></DIV>&gt; for(; n &gt; 1; r *= n, --n); 
<DIV></DIV>&gt; return r; 
<DIV></DIV>&gt;} 
<DIV></DIV>&gt; 
<DIV></DIV>&gt;If you wanted to do the same with while loop then you could use: 
<DIV></DIV>&gt; 
<DIV></DIV>&gt;b = 1; // first initialise b 
<DIV></DIV>&gt;while(a &gt; 1) 
<DIV></DIV>&gt;{ 
<DIV></DIV>&gt; b = b * a--; // or b *= a--; 
<DIV></DIV>&gt;} 
<DIV></DIV>&gt; 
<DIV></DIV>&gt;I hope from that you can figure out what you were doing wrong. The only reason to bring in a third variable would be to avoid changing 'a', and then you would just assign 'a' to a temporary variable i.e. 't' and then operate on it. Note that you don't need to multiply by 1 so it's 'a &gt; 1' and not 'a &gt;= 1', but it's a minor improvement. 
<DIV></DIV>&gt; 
<DIV></DIV>&gt;Jason. 
<DIV></DIV>&gt; ----- Original Message ----- 
<DIV></DIV>&gt; From: Daniel Glenfield 
<DIV></DIV>&gt; To: dev...@li... 
<DIV></DIV>&gt; Sent: Sunday, October 21, 2001 11:00 PM 
<DIV></DIV>&gt; Subject: [Dev-C++] factorial code additional 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; what is wrong? 
<DIV></DIV>&gt; I want to get the factorial of any number inputted 
<DIV></DIV>&gt; It must have three veriables btw 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; #include <STDIO.H>
<DIV></DIV>&gt; int main() 
<DIV></DIV>&gt; /* This is a program which calculates the factorial of a number */ 
<DIV></DIV>&gt; { 
<DIV></DIV>&gt; int a,b; 
<DIV></DIV>&gt; printf("Input number"); 
<DIV></DIV>&gt; scanf("%d",&amp;a 
<DIV></DIV>&gt; while (a &gt;= 1) 
<DIV></DIV>&gt; { 
<DIV></DIV>&gt; a*(a--); 
<DIV></DIV>&gt; b = a; 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; } 
<DIV></DIV>&gt; printf ("The factoral is %d\n", b ); 
<DIV></DIV>&gt; return 0; 
<DIV></DIV>&gt; } 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; 
<DIV></DIV>&gt; 
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