letters to touch tone number output - php

Question

I tried Googling this but not sure what's the best thing to look for. What I am trying to do is to translate a text input to output the letters of a touch tone phone. For example Hello World would output 43550 96153the idea is I'm trying to use the tropo voice api system and want the user to be able to enter their name as touch tone values and match that to their name as numbers in my database.
I'm assuming this can be done with a function along the lines of
$input= $touchtone_value;
$number_two_array (a,b,c);
if( $input==in_array($number_two_array)){
$output = '2';
}
I'm sure this will work. However, if there is a class out there or a simpler function than to break each letter into number arrays I think that would be a better way to do it. At this point this is a fairly open ended question as I have NO IDEA where to start as the best way to accomplish this.
EDIT: I found a solution, not sure it's the best one.
$input = strtolower('HELLO WORLD');
echo 'input: '. $input. "\n";
echo $output = 'output: '. strtr($input,'abcdefghijklmnopqrstuvwxyz', '22233344455566677778889999');
input:hello world
output: 43556 96753
Now I just need to find a way to remove white space :)
http://codepad.org/Ieug0Zuw
Source: code a number into letters

Answer 1

PHP provides a function called strtr which does string translations. The first argument is what you want to translate, the second is the original characters, the third is the replacement characters. Below is a function that should do what you want. Edit: Updated my sample to strip out any characters that aren't supported (anything other than a-z or a space)
<?php
function get_tones($inp) {
$from = 'abcdefghijklmnopqrstuvwxyz ';
$to = '222333444555666777788899990';
// convert the input to lower case
$inp = strtolower($inp);
// remove anything that isn't a letter or a space
$inp = preg_replace('/[^a-z ]/', '', $inp);
return strtr($inp, $from, $to);
}
assert(get_tones('Hello world') == '43556096753');
assert(get_tones('Hell234"*&o world') == '43556096753');
assert(get_tones('ALEX') == '2539');
assert(get_tones(' ') == '0000');

Answer 2

How about a structure like this... NOTE: This will ignore invalid 'letters' like spaces, punctuation, etc..
LIVE DEMO http://codepad.org/pQHGhm7Y
<?php
echo getNumbersFromText('Hello There').'<br />';
echo getNumbersFromText('This is a really long text string').'<br />';
function getNumbersFromText($inp){
$result=array();
$inp = strtolower($inp);
$keypad = array('a' => '2', 'b' => '2', 'c' => '2', 'd' => '3',
'e' => '3', 'f' => '3', 'g' => '4', 'h' => '4',
'i' => '4', 'j' => '5', 'k' => '5', 'l' => '5',
'm' => '6', 'n' => '6', 'o' => '6', 'p' => '7',
'q' => '7', 'r' => '7', 's' => '7', 't' => '8',
'u' => '8', 'v' => '8', 'w' => '9', 'x' => '9',
'y' => '9', 'z' => '9');
for ($x=0; $x<strlen($inp); $x++){
$letter = $inp[$x];
if ($keypad[$letter]) $result[]= $keypad[$letter];
}
return implode('',$result);
}
?>

Answer 3

I'm not sure I understand exactly what you are asking:
Your input is words, and you want to output the corresponding numbers?
Your input is numbers, and you want to output the corresponding words?
In case (1), it's simple, just use an array that maps each letter of the alphabet to the corresponding numbers (i.e. key is letter, value is number). You can then just iterate over the characters of the input, and output using the corresponding element in the array.
Case (2) is a bit trickier. You can build a Trie from your list of names, and use it to do the lookup.