Welcome to Dream.In.Code
Getting Help is Easy!

Join 99,783 Programmers for FREE! Ask your question and get quick answers from experts. There are 1,549 online right now! We've got more than 500 tutorials and 2,000 snippets. Join and find out why Dream.In.Code is the #1 programming help community on the internet! Registration is fast and FREE... Join Now!



Random number within a given range

 
Reply to this topicStart new topic

> Random number within a given range

no2pencil
Group Icon



post 6 May, 2008 - 07:04 PM
Post #1


Random number within a given range

Here are the steps in order to generate random numbers from a given range.
1st, we get a return value from the random() function. This value will be between 0.0 & 1.0.
We then multiply this value with the difference of the maximum value, & one less than the minumum value in our given range.
After that, we use the floor() function, to convert it into an integer.
Lastly, add the minimum value of our given range, to the number we came up with from above.

CODE

<html>
<head>
<title>JavaScript Random Numbers</title>
</head>
<body>
<script language=JavaScript>
<!--
var rand_no = Math.floor((10-4)*Math.random()) + 5;
alert(rand_no);
-->
</script>
</body></html>


The code above generates a random number between 5 and 10. With 5 being our minimum, & 10 being our maximum.

Random number within an array

CODE

<html>
<head>
<title>JavaScript Random Numbers</title>
</head>
<body>
<script language="JavaScript">
<!--
movie = new Array
movie[1]="Casablanca"
movie[2]="The Wizard of Oz"
movie[3]="The Dirty Dozen"
movie[4]="Who Framed Roger Rabbit?"
movie[5]="The Five Heartbeats"
movie[6]="Battleground"
movie[7]="The Life and Times of Hank Greenberg"
movie[8]="The Battle for Heavy Water"
movie[9]="My Blue Heaven"

var rand_no = Math.floor((9-1)*Math.random()) + 1;

document.write(movie[rand_no]);
-->
</script>
</body></html>


The code example above generates a random number between 1 and 9. Again, with 1 being our minimum, & 9 being our maximum.


Register to Make This Ad Go Away!

mocker
**



post 7 May, 2008 - 09:35 AM
Post #2
Just to add to your last example.. if you want to get a random element of the array, it usually is not a good idea to hardcode how many elements are in that array. I use the following code to get a random element of an array links[] and write it to a div

CODE

function newLink(){
var lmax = links.length;            
var random_num = (Math.floor((Math.random()*lmax)+1));
var d = document.getElementById('rlink');        
var newhtml = "<a href='"+links[random_num]+"'>"+links[random_num]+"</a>";
d.innerHTML = newhtml;
};


Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Lo-Fi Version Time is now: 7/25/08 01:17AM

Live Help!

Tutorials

Programming

Web Development

Reference Sheets

Code Snippets

Bye Bye Ads

Free DIC T-Shirt

T-Shirt Example

Related Sites

Monthly Drawing

Thumb Drive

Partners

Top Contributors

Top 10 Kudos This Month
-->