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print_range

Language/Type: PHP recursion

Write a recursive function named print_range that accepts integer parameters $x and $y and prints the sequential integers between $x and $y inclusive in a particular format. The first half should be printed with the greater-than character (">") separating consecutive values. The second half should be printed with the less-than character ("<") separating consecutive values. When there are two values in the middle of the range, those two values should be separated by a pair of dashes ("--"), as shown in the second example output below. The following table shows several calls and their expected output:

Call Output
print_range(1, 9); 1 > 2 > 3 > 4 > 5 < 6 < 7 < 8 < 9
print_range(1, 10); 1 > 2 > 3 > 4 > 5 -- 6 < 7 < 8 < 9 < 10
print_range(23, 29); 23 > 24 > 25 > 26 < 27 < 28 < 29
print_range(13, 14); 13 -- 14
print_range(-8, -8); -8

Notice that in the first output, 5 is in the middle with the numbers before it separated by greater-than and the numbers after it separated by less-than. In the second output, 26 is in the middle with numbers before it separated by greater-than and numbers after it separated by less-than. The last output has no separators because that range includes one number.

Your function should throw an Exception if $x is greater than $y.

Constraints:

  • Do not use any loops; you must use recursion.
  • Do not use any auxiliary data structures (e.g. arrays) to this problem.
Function: Write a PHP function as described, not a complete program.

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