Rename .go files to match package rename

convertroman.go

@@ -0,0 +1,33 @@
+package convertroman
+
+// Currently only supports Roman Numerals without viniculum (1-3999) and will throw an error for
+// numbers outside of that range. See here for details on viniculum:
+// https://en.wikipedia.org/wiki/Roman_numerals#Large_numbers
+
+import (
+	"errors"
+)
+
+var (
+	// IntegerOutOfBounds - error for when the integer provided is invalid and unable to be converted to a roman numeral
+	IntegerOutOfBounds = errors.New("integer must be between 1 and 3999")
+
+	// lookup arrays used for converting from an int to a roman numeral extremely quickly.
+	// method from here: https://rosettacode.org/wiki/Roman_numerals/Encode#Go
+	r0 = [10]string{"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"}
+	r1 = [10]string{"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"}
+	r2 = [10]string{"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"}
+	r3 = [4]string{"", "M", "MM", "MMM"}
+)
+
+// FromInt converts an integer value to a roman numeral string.
+// An error is returned if the integer is not between 1 and 3999.
+func FromInt(input int) (string, error) {
+	// ensure provided integer is within the valid range
+	if input < 1 || input > 3999 {
+		return "OOB", IntegerOutOfBounds
+	}
+
+	// convert the integer to a roman numeral string and return it
+	return r3[input%1e4/1e3] + r2[input%1e3/1e2] + r1[input%100/10] + r0[input%10], nil
+}