I hope some can help me with a beginner question (this is specifically running on Arduino, but I suspect it is a much more fundamental C++ question than that).

I do not understand why the following "switch" statement outputs both "Channel 1" and "Channel 2" statements:

void setup() {
  delay(100);
  Serial.begin(57600);
  delay(100);

  int channel = 1;

  switch (channel) {
    case 1:
      Serial.println("Channel 1");
    case 2:
      Serial.println("Channel 2");
  }
}

void loop() {

}

I have read that the switch statements "follow-though" or "cascade", i.e. I understand that if condition 1 is satisfied then the code will still go on to check the subsequent conditions regardless (and you can add an explicit "break" command to jump out). This is all fine.

But I don’t understand that then the second expression evaluates to true (because the integer variable channel=1, and it should only evaluate true when channel=2).

What am I missing here?

Thank you!

>Solution :

You seem to expect it to be like

if (channel == 1) 
    Serial.println("Channel 1"); 
if (channel == 2) 
   Serial.println("Channel 2");

but it’s actually like

if (channel == 1)
    goto case1;
if (channel == 2)
    goto case2;
goto none;
case1:
    Serial.println("Channel 1");
case2:
    Serial.println("Channel 2")
none: