Unique integer from string?

[Nathan Ridley]

Is it possible to generate a unique number from a string of say 50-100 characters? Is that what a "hash" is? If so, how do you do it? NATHAN RIDLEY Web Application Developer email: nathan @ netlab.com.au [remove the spaces before and after the @ symbol]

[amatyasik]

Hello! I'm not a guru but i think MD5 encryption is a solution for this case Bye

[Heath Stewart]

While it's not guaranteed to be unique, it is mathematically impropable (not impossible) to get the same hash. You can generate a digest over your string like so:

public string Digest(string value)
{
if (value == null) throw new ArgumentNullException("value");
byte[] buffer = Encoding.Unicode.GetBytes(value); // Or whatever encoding
MD5 md5 = MD5.Create();
byte[] hash = md5.ComputeHash(buffer);
return ConvertToHex(hash);
}
public string ConvertToHex(byte[] buffer)
{
if (buffer == null) throw new ArgumentNullException();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < buffer.Length; i++)
sb.AppendFormat("{0:X2}", buffer[i]);
return sb.ToString();
}

Microsoft MVP, Visual C# My Articles

[Jeff Varszegi]

Hash function definition When people talk about hashing data, they're passing it through a hash function. Hash functions are one-way functions at least in the sense that data over an unconstrained range may be made to fit into a constrained range; however, it's sometimes possible to figure out possible input values from some output. MD5 is an often-used hashing algorithm. The single most popular use for hashing, in my experience, is to store passwords in a somewhat secure way. Many servers don't store a plain-text version of a password, or can be configured that way; instead, they store the hashed version, and when some client requests authentication, they take the passed password, hash it, and compare it to the hashed version. Regards, Jeff Varszegi EEEP!

[Nathan Ridley]

Thanks guys for the answers. Very helpful! :) NATHAN RIDLEY Web Application Developer email: nathan @ netlab.com.au [remove the spaces before and after the @ symbol]

[Jeff Varszegi]

You're welcome! Regards, Jeff Varszegi EEEP!