Prints data to the serial port as human-readable ASCII text. This command can take many forms. Numbers are printed using an ASCII character for each digit. Floats are similarly printed as ASCII digits, defaulting to two decimal places. Bytes are sent as a single character. Characters and strings are sent as is. For example:

  • Serial.print(78) gives "78"
  • Serial.print(1.23456) gives "1.23"
  • Serial.print('N') gives "N"
  • Serial.print("Hello world.") gives "Hello world."

An optional second parameter specifies the base (format) to use; permitted values are BIN(binary, or base 2), OCT(octal, or base 8), DEC(decimal, or base 10), HEX(hexadecimal, or base 16). For floating point numbers, this parameter specifies the number of decimal places to use. For example:

  • Serial.print(78, BIN) gives "1001110"
  • Serial.print(78, OCT) gives "116"
  • Serial.print(78, DEC) gives "78"
  • Serial.print(78, HEX) gives "4E"
  • Serial.print(1.23456, 0) gives "1"
  • Serial.print(1.23456, 2) gives "1.23"
  • Serial.print(1.23456, 4) gives "1.2345"

You can pass flash-memory based strings to Serial.print() by wrapping them with F(). For example:

Serial.print(F("Hello World"))

To send data without conversion to its representation as characters, use Serial.write().



Serial.print(val, format)

Parameter Values

  • Serial: serial port object. See the list of available serial ports for each board on the Serial main page.
  • val: the value to print. Allowed data types: any data type.

Return Values

  • print() returns the number of bytes written, though reading that number is optional. Data type: size_t.

Example Code

/* Uses a for loop to print numbers in various formats. */ void setup() { Serial.begin(9600); // open the serial port at 9600 bps: } void loop() { // print labels Serial.print("NO FORMAT"); // prints a label Serial.print("\t"); // prints a tab Serial.print("DEC"); Serial.print("\t"); Serial.print("HEX"); Serial.print("\t"); Serial.print("OCT"); Serial.print("\t"); Serial.print("BIN"); Serial.println(); // carriage return after the last label for (int x = 0; x < 64; x++) { // only part of the ASCII chart, change to suit // print it out in many formats: Serial.print(x); // print as an ASCII-encoded decimal - same as "DEC" Serial.print("\t\t"); // prints two tabs to accomodate the label lenght Serial.print(x, DEC); // print as an ASCII-encoded decimal Serial.print("\t"); // prints a tab Serial.print(x, HEX); // print as an ASCII-encoded hexadecimal Serial.print("\t"); // prints a tab Serial.print(x, OCT); // print as an ASCII-encoded octal Serial.print("\t"); // prints a tab Serial.println(x, BIN); // print as an ASCII-encoded binary // then adds the carriage return with "println" delay(200); // delay 200 milliseconds } Serial.println(); // prints another carriage return }


For information on the asyncronicity of Serial.print(), see the Notes and Warnings section of the Serial.write() reference page.

See Also

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