Question

Create a program that executes changes over a string.

First, you start with an empty string, then you receive the commands.

You will be receiving commands until the "End" command. There are five  possible commands:

• "Add {string}"
  • Concatenate {string} to the string.
•  "Upgrade {char}"
  • Find all occurances of {char} and replace it with the ASCII code plus one.
• "Print"
  • Print the string.
• "Index {char}"
  • Find all the indeces where {char} occurs, then print them separated by a space if no occurances – print "None".
• "Remove {string}"
  • Remove all occurances of {string} from the string.

Input:

• On each line, until the "End" command is received, you will be receiving commands.
• All commands are case sensitive.
• The input will always be valid.

Output:

• Print the output of every command in the format described above.

Examples:

Answer 1

Here is my solution:

<?php

$string = "";

$input = readline();

while ($input != "End") {

    $args = explode(" ", $input);

    $command = $args[0];

    switch ($command) {
        case 'Print':
            echo $string . PHP_EOL;
            break;
        case 'Add':
            $concat = $args[1];
            $string .= $concat;
            break;
        case 'Upgrade':
            $char = $args[1];
            $replace = chr(ord($char) + 1);
            $string = str_replace($char, $replace, $string);
            break;
        case 'Index':
            $indeces = [];
            $search = $args[1];
            for ($i = 0; $i < strlen($string); $i++) {
                if ($string[$i] == $search) {
                    $indeces[] = $i;
                }
            }
            if (count($indeces) > 0) {
                echo implode(" ", $indeces) . PHP_EOL;
            } else {
                echo "None";
            }
            break;
        case 'Remove':
            $remove = $args[1];
            $string = str_replace($remove, "", $string);
            break;
    }

    $input = readline();
}