Calculation always zero?

Projects Programming
4

While true for uninitialized GLOBAL variables it's a bad assumption that uninitialized LOCAL variables will be zero. Uninitialized LOCAL variables will contain whatever garbage is on the stack.

Something a little more easy to follow -

const unsigned long ONE_SECOND  = 1000UL;

void loop()
{
    int Ua      = analogRead(A0);
    Serial.print("Ua: ");       Serial.println(Ua);

    int Ub      = analogRead(A1);
    Serial.print("Ub: ");       Serial.println(Ub);

    delay(ONE_SECOND);

    int Dehnung = Ua - Ub;
    Serial.print("Dehnung: ");  Serial.println(Dehnung);
}

void setup()
{
    Serial.begin(9600);
}