Solved

C Random Numbers 0.0 to 1.0

Posted on 2006-11-04
5
366 Views
Last Modified: 2010-05-18
Hi,
I need to generate random numbers using C in the following range:
0.0 <= X <= 1.0

That will give us the following possible values
0.0
0.1
0.2
...
0.9
1.0

So far, I have been able to generate random numbers, but not to the tenth place.  If anyone knows how to modify my code, or write better code, that is what I need.  Here is my code:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
int main() {
srand(time(NULL));

double rnum;
int i;

for(i=0; i<=20; i++) {
    rnum = 1.1 * (float) rand() / (float) RAND_MAX;
    printf("Number: %lf\n", rnum);
}

return 0;
}

0
Comment
Question by:deadite
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
5 Comments
 
LVL 13

Accepted Solution

by:
marchent earned 75 total points
ID: 17874402
>>rnum = 1.1 * (float) rand() / (float) RAND_MAX;
rnum = (float)(rand() % 11) /10;

~marchent~
0
 
LVL 8

Author Comment

by:deadite
ID: 17874419
marchent,

That worked perfect, except my printf line still outputs the extra 0's.  Is there a way to get rid of them?  For example:

0.600000
1.000000
0.200000

Thanks
0
 
LVL 84

Assisted Solution

by:ozo
ozo earned 25 total points
ID: 17874650
printf("Number: %.1f\n", rnum);
0
 
LVL 8

Author Comment

by:deadite
ID: 17874983
Ozo,
Sorry for the confusion.  I meant get rid of the extra 0's so the number stored is X.X  not X.XXXXXX.  However, your printline shows the results I need, but doesn't store the ones I need.

Thanks
0
 
LVL 84

Expert Comment

by:ozo
ID: 17875050
I'm sorry, I don't understand what you mean when you say the number stored is X.X  not X.XXXXXX
the number is not stored as a string of ASCII digits, the number is stored as a float,
which probably does not even have an exact representation for 0.1
0

Featured Post

On Demand Webinar - Networking for the Cloud Era

This webinar discusses:
-Common barriers companies experience when moving to the cloud
-How SD-WAN changes the way we look at networks
-Best practices customers should employ moving forward with cloud migration
-What happens behind the scenes of SteelConnect’s one-click button

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A short article about problems I had with the new location API and permissions in Marshmallow
This is about my first experience with programming Arduino.
An introduction to basic programming syntax in Java by creating a simple program. Viewers can follow the tutorial as they create their first class in Java. Definitions and explanations about each element are given to help prepare viewers for future …
In this fifth video of the Xpdf series, we discuss and demonstrate the PDFdetach utility, which is able to list and, more importantly, extract attachments that are embedded in PDF files. It does this via a command line interface, making it suitable …

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question