Categories: Programming

PHP: rand() vs. mt_rand() – what is more accurate, what is faster?

Posted by Raffael on Posted in PHP Tagged , , , , ,

After I was pointed out, that it would be better to use the PHP function mt_rand() instead of rand() for generating random numbers (because mt_rand() should be more accurate), I decided to investigate on that statement. But at first, where is the difference between rand() and mt_rand()?
By use of mt_rand() you can generate random numbers just like with the rand() function. The function call also looks equal on both functions. Though the PHP documentation says mt_rand() is up to 4-times faster and would be create more random/arbitrary numbers. By implication this would mean, that the rand() function creates inaccurate random numbers.
I was not aware of this problem, but after some googleing I discovered that there are a lot of people who think that mt_rand() is the better function. However I had to notice that most of the contributions which complain that rand() is not clean are a “little older”.
Often cited […]

How to get website header information in C#

Posted by Raffael on Posted in C#.Net Tagged , , , , , ,

With the following function you can easily retrieve a list of website headers in C#. The function needs only the url of a webpage to collect the data. If the function is successfully executed, you’ll get a Dictionary, typed as <string, string>, as return value. This Dictionary<string, string> contains all the headers of the webpage, whose url you passed by at function call time.

//Don’t forget to set the using-directive ;)
using System.Net;

//…

public Dictionary getHeaders(string url)
{
//Dictionary which shall contain the header information
Dictionary header = new Dictionary();

//Create webrequest
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);

//Create response object
HttpWebResponse response = (HttpWebResponse)request.GetResponse();

//Read all headers from the response
foreach (string headerItem in response.Headers)
{
//Add header to the dictionary
[…]

Download source code of a website in C#

Posted by Raffael on Posted in C#.Net Tagged , , , , , , ,

With the help of the follwing short C# snippet, you’re able to receive the html code / source of any website as string. Such a function is useful, for example, if you want to parse some information from a website for later use.
Thus the snippet works, you have to add the following two using directives to the header of your source.

using System.Net;
using System.IO;

The function itself looks like this:

public string getHTML(string url)
{
//Create request for given url
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);

//Create response-object
HttpWebResponse response = (HttpWebResponse)request.GetResponse();

//Take response stream
StreamReader sr = new StreamReader(response.GetResponseStream());

//Read response stream (html code)
string html = sr.ReadToEnd();

//Close streamreader and response
sr.Close();
response.Close();

//return source
return html;
}

A function call could look like this:

getHTML("http://www.code-bude.net");

If you’ve got suggestions or even problems with the snippet, just write a comment.

How to easily record from a webcam in C#

Posted by Raffael on Posted in C#.Net, Tutorials Tagged , , , , , , , , , ,

What is the easiest way to use a webcam in C# and record from it? If you search for an answer to this question you’ll find a lot of articles in the internet but most of them are many pages long and very confusing. However that isn’t really necessary. With the aid of the AForge.NET library you can do the given task really easy. Just a few lines of C# code are enough to drive your webcam and capture images from it. In the following I’ll show you how to handle the AForge library.
What do you need?

The AForge.Video.dll together with the AForge.Video.DirectShow.dll
Both dlls can be found on the AForge website inside the “(libs only)” zip-archive.
A simple winforms-application, with a picturebox on its gui
A webcam. For example this one:No products found.
Basic C#-knowledge. If not exists, read this: No products found.

At first you have to reference the both dlls and write the using-statements […]