convert_temperature <- function(value, from_unit, to_unit) {
  if (from_unit == "C" & to_unit == "F") {
    return((value * 9/5) + 32)
  } else if (from_unit == "F" & to_unit == "C") {
    return((value - 32) * 5/9)
  } else if (from_unit == "C" & to_unit == "K") {
    return(value + 273.15)
  } else if (from_unit == "K" & to_unit == "C") {
    return(value - 273.15)
  } else if (from_unit == "F" & to_unit == "K") {
    return((value - 32) * 5/9 + 273.15)
  } else if (from_unit == "K" & to_unit == "F") {
    return((value - 273.15) * 9/5 + 32)
  } else {
    return("Invalid input! Please use 'C', 'F', or 'K' as units.")
  }
}

# Example usage:
convert_temperature(100, "C", "F")  # Converts 100°C to Fahrenheit
## [1] 212
convert_temperature(32, "F", "C")   # Converts 32°F to Celsius
## [1] 0
convert_temperature(0, "C", "K")    # Converts 0°C to Kelvin
## [1] 273.15