function don't return

unsigned int countUp;



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

void boop(){
      while(countUp++ < 67000){
            Serial.println(countUp);
  } 

  delay(15000);
  return;

}

How do you stop a program?

JPDaviau

Do you have a question?

I think that I see his main problem. (Of three).

See int - Arduino Reference

while(countUp++ < 67000)Look up the value of the largest possible “unsigned int” on an Arduino.

This must be "do my school project" season.

“How do you stop a program?”

void setup() {
  // put your setup code here, to run once:


}


void loop() {
  // put your main code here, to run repeatedly:
  while (1) {
    // do nothing until Reset is pressed.
  }
}

SteveMann:
This must be "do my school project" season.

When you put return; in C the program return
when you write break; it does break out of the loop

Jean24816:
When you put return; in C the program return
when you write break; it does break out of the loop

Neither of which, of itself, stops a program.

When the main() return the program continue?

main(), which is normally hidden from you in Arduino, calls setup() and then repeatedly, loop().

SteveMann:
This must be "do my school project" season.

Happens every year around the start. Pretty soon it will drop off as the class sizes start to shrink IYKWIM.

CrossRoads:
"How do you stop a program?"

void setup() {

// put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:
  while (1) {
    // do nothing until Reset is pressed.
  }
}

Thank you from a 72 years student. ;p).

unsigned int    countUp = 65000;   // the   INT_MAX = 65535

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  doit();
  Serial.println(countUp);
}

void loop() {
}

void doit() {
  do {
    Serial.println(countUp);
  } while (countUp++ != 0 );

  return;
}