Format several integers in a fixed buffer.
Arduino / C: snprintf limits writes to the buffer size and includes a terminating null byte.
#include <stdio.h>
void setup() {
Serial.begin(9600);
char text[24];
snprintf(text, sizeof(text), "id=%d,count=%d", 7, 12);
Serial.println(text);
}
void loop() {
}Expected output EXAMPLE
id=7,count=12
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. snprintf limits writes to the buffer size and includes a terminating null byte.
Tested on Ubuntu 24.04.5 LTS · · Uno R3 / ATmega328P at 16 MHz; simavr 1.6+dfsg-3build2 · bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; 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
e3908b34530a92b26b9e65f95c23e13a0605b1facec9c800ddc5f13e572f196a- Dependencies
- bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; 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": "", "pin_input": "none"}
Observed standard output
id=7,count=12
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.