Another story on random == unique wtf

ounos

This gem existed some years ago in our codebase.

The problem that the ingenious programmer tried to solve? Create a handful of artificial namespace prefixes for use in some generated xml output.

private String createname(){
	char chars []= {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};

	String str = String.valueOf(chars);
	String name = "";

	for(int i=0; i<3; i++){
		name = name + str.charAt((int)((Math.random()*26)%26));
	}
	return (name);
}

I once saw a prefix named "bug". "Curious", I thought, and ignored it.

The second time it caught my attention was when it exploded.

The moral: always pay attention to what your code tries to tell you.

DOA

I think you should just change that 3 to 4 and wait for the really interesting words to show up.

ounos

Yeah, but why restrain myself to that? I could just change it to 1,145,589 and wait till the Iliad comes out. Epic poetry embedded in XML? Customers would love it!

ounos

butitcouldusesomespacetheretooandperhapssomepunctuation

smxlong

@DOA said:

I think you should just change that 3 to 4 and wait for the really interesting words to show up.

Words like 'aaaa'? Because the only thing this function will ever generate is a stream of 'a'.

The random value is first multiplied by 26, making it a multiple of 26. Then it is modded by 26, which will always be zero.

julmu

@smxlong said:

@DOA said:
I think you should just change that 3 to 4 and wait for the really interesting words to show up.

Words like 'aaaa'? Because the only thing this function will ever generate is a stream of 'a'.
The random value is first multiplied by 26, making it a multiple of 26. Then it is modded by 26, which will always be zero.

http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Math.html

public static double random()

Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0.

ounos

@julmu said:

@smxlong said:
@DOA said:
I think you should just change that 3 to 4 and wait for the really interesting words to show up.

Words like 'aaaa'? Because the only thing this function will ever generate is a stream of 'a'.
The random value is first multiplied by 26, making it a multiple of 26. Then it is modded by 26, which will always be zero.

http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Math.html

public static double random()

Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0.

I nominate you, sir, for the most brillant person of the thread. Congrats!

julmu

@ounos said:

I nominate you, sir, for the most brillant person of the thread. Congrats!

I don't get it. Why do you think that I'm brillant?

ounos

Your browser settings must be hiding the <irony> tags all around. But you can't see that.