danke!
Es funktioniert allerdings bei Arduino offenbar auch ohne <int>, aber ich werde es mir merken, ggf für den Raspi!
Code:

//---------------------------------------------------------
// Bubble Sort
//---------------------------------------------------------

template <typename VTYPE>  void bubblesort(VTYPE *array, int length) {
  VTYPE tmp;

  for (int i=0; i<length-1; i++)     {
    for (int j=0; j<length-i-1; j++)  {
      if (array[j] > array[j+1])       {
        tmp = array[j];
        array[j] = array[j+1];
        array[j+1] = tmp;
      }
    }
  }
}




void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("\nSerial started...\n");
  
  int intarray[3]={3,5,1};
  bubblesort(intarray, 3);
  for(int i=0; i<3; i++) Serial.println(intarray[i]);

  float floatarray[3]={5.0,1.0,3.0};
  bubblesort(floatarray, 3);
  for(int i=0; i<3; i++) Serial.println(floatarray[i]);
}

void loop() {
  // put your main code here, to run repeatedly:

}
Ausgabe:
Code:
Serial started...

1
3
5
1.00
3.00
5.00