Encode tinyurl-style

foxroberts

Hi.

I have a several numbers (1282 or 2845) which I want to encode "tinyurl"-code-style (gd2h or s9d5), because a big number could be displayed with a few letters. My idea:

I use an array('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','0','1','2','3','4','5','6','7','8','9') which contains all the letters and digits I want to use in my code.

My encoded numbers should look like this:
1 becomes a, 2 becomes b, 3 becomes c, ... , 36 becomes 9, 37 becomes aa, 38 becomes ab, 39 becomes ac.

I have no idea how to calculate it without a big loop. That of course would slow down the script a lot... perhaps you have an idea!

Thank you in advance!
Fox

etully

I would think of this as converting a number from Base 10 to Base 36. Write a function that can take in a number in Base 10 and convert it to Base 36. You will also need a reverse function to convert Base 36 numbers to Base 10.

First, make an array called $letter_array which has all the leters and number symbols in their respective postions. Then I would construct a loop to find how many characters (columns) will be required in Base 36 to represent the Base 10 number (call the number colums N).. Then divide the Base 10 number by 36^N to find the number that should go into that column. Either construct a string or an array where the first (left most) column is $letter_array[ floor( X / 36^N ) ]. Then subtract floor(that number * 36^N) from X and repeat the loop for the next postion.

So really, it's just like Hex where 0=0, 1=1 ... 9=9, A=10, B=11 ... F=15, 10=16, 11=17 etc.

except that instead of having 16 characters to work with, your function will have 36 characters to work with.

NogDog

Just use the [man]base_convert/man function.

etully

Just use the base_convert() function.

Well yeah, I suppose if you like taking the easy route, sure.

Ahem.. I should have suspected that there was a base convert function.

NogDog

If the unofficial motto for Perl is, "There's more than one way to do it," then the motto for PHP should be, "There's probably a built-in function for that." 😉

foxroberts

Thank you very much for your help!