Temperature Conversion

Two scales, one formula each, and everything that goes wrong when integers and floats meet:

F = C * 9/5 + 32
C = (F - 32) * 5/9

Write c * 9 / 5 in Go and it works, because c is a float64 and the untyped constants adopt its type. Write 9 / 5 on its own and you get 1: two untyped integer constants divide as integers. The habit that saves you is writing the constants as 9.0 and 5.0 so the intent is on the page rather than inferred from a neighbouring variable.

Rounding is the other half. int(f) truncates toward zero, so int(70.7) is 70 and int(-3.6) is -3. When you want the nearest value you say so with math.Round, which rounds halves away from zero, and only then convert.

Task

Finish the five functions in main.go.

1. CToF(c float64) float64 and FToC(f float64) float64 - the two formulas. -40 is the same in both scales, and the tests check that converting there and back lands where it started.
2. RoundTenth(v float64) float64 rounds to one decimal place, halves away from zero: 1.25 becomes 1.3 and -1.25 becomes -1.3.
3. FahrenheitWhole(c float64) int converts to Fahrenheit and rounds to the nearest whole degree. 21.5°C is 70.7°F, so the answer is 71, not 70.
4. Report(c float64) string renders one line with both scales to one decimal: Report(21.5) is "21.5°C = 70.7°F".

Hints

• math.Round is in the math package, which main.go does not import yet. Add it; an unused import is a compile error, which is why it was left out.
• Rounding to a decimal place is rounding after a shift: math.Round(v*10) / 10. The same trick with 100 gives you two places.
• FahrenheitWhole is math.Round then int(...). Reverse those two and the conversion truncates before the rounding ever happens.
• %.1f in fmt.Sprintf prints one decimal place and rounds for you, so Report does not need RoundTenth. Rounding a value and rounding its display are different jobs; this challenge asks for both so the difference has somewhere to show.
• The degree sign in the expected output is °, one rune and two bytes in UTF-8. Paste it rather than typing a lookalike, and note that len("°C") is 3 - exactly what the previous challenge was about.
• The tests compare floats with a tolerance instead of ==. 0.1 + 0.2 is not 0.3 in binary floating point, in Go or anywhere else, so an exact comparison on computed floats is a bug waiting for the right input.