php switch case statement to handle ranges - php

Question

I'm parsing some text and calculating the weight based on some rules. All the characters have the same weight. This would make the switch statement really long can I use ranges in the case statement.
I saw one of the answers advocating associative arrays.
$weights = array(
[a-z][A-Z] => 10,
[0-9] => 100,
['+','-','/','*'] => 250
);
//there are more rules which have been left out for the sake of clarity and brevity
$total_weight = 0;
foreach ($text as $character)
{
$total_weight += $weight[$character];
}
echo $weight;
What is the best way to achieve something like this?
Is there something similar to the bash case statement in php?
Surely writing down each individual character in either the associative array or the switch statement can't be the most elegant solution or is it the only alternative?

Answer 1

Well, you can have ranges in switch statement like:
//just an example, though
$t = "2000";
switch (true) {
case ($t < "1000"):
alert("t is less than 1000");
break
case ($t < "1801"):
alert("t is less than 1801");
break
default:
alert("t is greater than 1800")
}
//OR
switch(true) {
case in_array($t, range(0,20)): //the range from range of 0-20
echo "1";
break;
case in_array($t, range(21,40)): //range of 21-40
echo "2";
break;
}

Answer 2

$str = 'This is a test 123 + 3';
$patterns = array (
'/[a-zA-Z]/' => 10,
'/[0-9]/' => 100,
'/[\+\-\/\*]/' => 250
);
$weight_total = 0;
foreach ($patterns as $pattern => $weight)
{
$weight_total += $weight * preg_match_all ($pattern, $str, $match);;
}
echo $weight_total;
*UPDATE: with default value *
foreach ($patterns as $pattern => $weight)
{
$match_found = preg_match_all ($pattern, $str, $match);
if ($match_found)
{
$weight_total += $weight * $match_found;
}
else
{
$weight_total += 5; // weight by default
}
}

Answer 3

You can specify the character range using regular expression. This saves from writing a really long switch case list. For example,
function find_weight($ch, $arr) {
foreach ($arr as $pat => $weight) {
if (preg_match($pat, $ch)) {
return $weight;
}
}
return 0;
}
$weights = array(
'/[a-zA-Z]/' => 10,
'/[0-9]/' => 100,
'/[+\\-\\/*]/' => 250
);
//there are more rules which have been left out for the sake of clarity and brevity
$total_weight = 0;
$text = 'a1-';
foreach (str_split($text) as $character)
{
$total_weight += find_weight($character, $weights);
}
echo $total_weight; //360

Answer 4

Much different ways to do this.
$var = 0;
$range_const = range(10,20);
switch ($var) {
case 1: $do = 5; break; # 1
case 2: $do = 10; break; # 2
case 3:
case 4:
case 5: $do = 15; break; # 3, 4, 5
default:
if ($var > 5 && $var < 10) { # High performance (6..9)
$do = 20;
} else if (in_array($var, $range_const, true)) { # Looks clear (10..20)
$do = 25;
} else { # NOT in range 1..20
$do = -1;
}
}
print($do);
There no direct range X..Y compares because $var checks to true in each step, but this allows do some nice cheating like this...
$in = create_function('$a,$l,$h', 'return $a>=$l && $a<=$h;');
$var = 4;
switch (true) {
case ($var === 1): echo 1; break;
case ($var === 2): echo 2; break;
case $in($var, 3, 5): echo "3..5"; break;
case $in($var, 6, 10): echo "6..10"; break;
default: echo "else";
}

Answer 5

If you have a more complex conditions, you can wrap them inside a function. Here's an oversimplified example:
$chartID = 20;
$somethingElse = true;
switch (switchRanges($chartID, $somethingElse)) {
case "do this":
echo "This is done";
break;
case "do that":
echo "that is done";
break;
default:
echo "do something different";
}
function switchRanges($chartID, $somethingElse = false)
{
if (in_array($chartID, [20, 30]) && $somethingElse === true) {
return "do this";
}
if (in_array($chartID, [20, 50]) && $somethingElse === false) {
return "do that";
}
}

Answer 6

I think I would do it in a simple way.
switch($t = 100){
case ($t > 99 && $t < 101):
doSomething();
break;
}