</>SnippetSearch. A little code. A lot of possibility.

Collect a serial line in a fixed buffer.

Read a short command without dynamic String allocation.

C++ snippet.ino 
char line[16];
byte length = 0;

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

void loop() {
  if (Serial.available() == 0) return;
  char value = (char)Serial.read();
  if (value == '\n') {
    line[length] = '\0';
    Serial.println(line);
    length = 0;
  } else if (value != '\r' && length < sizeof(line) - 1) {
    line[length++] = value;
  }
}

Expected output EXAMPLE

status

Details

Targets Arduino Uno R3 (ATmega328P, 16 MHz) with the Arduino AVR core. Open as a sketch in the Arduino IDE and select Arduino Uno. Serial output uses 9600 baud. Tested with simavr; electrical characteristics and physical wiring are outside this simulation. Send status followed by a newline. Lines longer than 15 characters are truncated; the buffer always has room for its terminator.

✓ Verified

Tested on Ubuntu 24.04.5 LTS · · Uno R3 / ATmega328P at 16 MHz; simavr 1.6+dfsg-3build2 · simavr 1.6+dfsg-3build2; arduino-cli Version: 1.5.1 Commit: 01f3d4f2b Date: 2026-06-05T10:22:17Z; Arduino AVR core 1.8.6

Test inputs, results and environment

The exact published code ran in a dedicated Linux test container with prepared inputs. Snippet process uid 65534 with a read-only root filesystem and temporary working files. Networking disabled. The exact sketch was compiled for Uno R3 and simulated at 16 MHz. UART output is shown below; compiler logs and measured GPIO traces are retained in the test evidence. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.

Architecture / host kernel
x86_64 / 6.18.54.1-microsoft-standard-WSL2
Snippet identity / locale
uid=65534, gid=65534 (unprivileged process) / C.UTF-8
Interpreter invocation
arduino-cli compile --fqbn arduino:avr:uno; uno-sim sketch.ino.elf (capture UART and D13 transitions)
Container image ID
sha256:ec91410a8f6ec3e985830b5e3a0560306d36f8c1c5ccd91a6699abe707123fa3
Code SHA-256
614b768cdd8523fb402192df69989ae096d78d51e8fc7502499f6c73811b82e0
Dependencies
simavr 1.6+dfsg-3build2; arduino-cli Version: 1.5.1 Commit: 01f3d4f2b Date: 2026-06-05T10:22:17Z; Arduino AVR core 1.8.6

Test input setup

These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.

Simulator inputs: {"sim_ms": 500, "serial_input": "status\n", "pin_input": "none"}

Observed standard output

status

Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.

# serial line # buffer # command