char buffers in Arduino

Fixed buffers avoid String's heap churn on a 2 KB board.

// Fixed char buffers avoid String's heap churn on a 2 KB board.
char label[16];
int batch = 0;

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

void loop() {
  batch++;
  // snprintf formats safely into the buffer, never past it.
  snprintf(label, sizeof(label), "batch-%03d", batch);
  Serial.print(label);
  Serial.print(" len=");
  Serial.println(strlen(label));
  delay(1000);
}

How it works

char label[16] reserves the space once, globally.
snprintf formats into it and never writes past the end.
strlen confirms what actually landed.

Keywords and builtins used here

Serial
begin
char
delay
int
loop
print
println
setup
sizeof
void

The run, in numbers

Lines: 17
Characters to type: 359
Tokens: 83
Three-star pace: 65 tpm

At the three-star pace of 65 tokens a minute, this run takes about 77 seconds.

Type this snippet

Step 1 of 3 in Data, step 19 of 27 in Language basics.

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