Serial.print bug ?

[Testato]

this code work only for an half,
it print only 12

void setup() {
Serial.begin(9600);
}
void loop() {
  Serial.print(1234);
  exit(0);    
}

[facchinm]

The report is missing "some" information... If the bug report refers to a UNO, it's quite normal that not all bytes are being written, since the 16u2 changes its behaviour based on the status of the 328 (and probably changes baud rate, too, I have no time to check).
However, adding a small delay between the print and exit should solve the issue.
Reopen if needed

[bengtmartensson]

Just two comments:

1. Normal programming practice says that you cannot rely everything to be output until you flush or close the buffer/stream. It appears that Serial.end should be used to close the stream.

2. exit is meaningless in the Arduino context.

[matthijskooijman]

Actually, I think exit() might be calling abort(), which IIRC disables interrupts and then starts looping infinitely. Because interrupts are disabled, serial output stops. If you insist on using exit(), make sure to call Serial.flush() to write all serial output first.

[MauroMombelli]

correct answer is then:

1. Normal programming practice says that you cannot rely everything to be output until you flush or close the buffer/stream. It appears that Serial.end should be used to close the stream.

2. exit() [...] disables interrupts and then starts looping infinitely. Because interrupts are disabled, serial output stops.

This happen because the Serial library is asynchronous, in this particular case reeling on the interrupt to put the next byte in the output buffer in the register that will take care of the communication.