Arduino File.println()


Prints data to a file on SD Card as human-readable ASCII text followed by a carriage return character (ASCII 13, or '\r') and a newline character (ASCII 10, or '\n').

File.println() is the same as File.print(), except for one thing: File.println() prints '\r' and '\n' character at the end while File.print() does not.

The File.println() function inherits from the Stream utility class.



file.println(data, format)

Parameter Values

  • File: an instance of the File class that is returned by
  • data: the value to print. Allowed data types: any data type.
  • format: (optional) specifies:

Return Values

  • println() returns the number of bytes written to the file. Data type: size_t.

Example Code

/* * Created by * * This example code is in the public domain * * Tutorial page: */ #include <SD.h> #define PIN_SPI_CS 4 File file; void setup() { Serial.begin(9600); if (!SD.begin(PIN_SPI_CS)) { Serial.println("SD CARD FAILED, OR NOT PRESENT!"); while (1); // don't do anything more: } Serial.println("SD CARD INITIALIZED."); SD.remove("arduino.txt"); // delete the file if existed // create new file by opening file for writing file ="arduino.txt", FILE_WRITE); if (file) { // print a character file.println('N'); // print a string file.println(); // print an empty line file.println(""); // print a float number float a = 1.23456; file.println(); // print an empty line file.println(a); // 2 decimal places by default file.println(a, 4); // 4 decimal places file.println(a, 5); // 5 decimal places file.println(a, 6); // 6 decimal places // print an interger number out in many formats: int x = 77; file.println(); // print an empty line file.println(x); // print as an ASCII-encoded decimal by default file.println(x, DEC); // print as an ASCII-encoded decimal file.println(x, HEX); // print as an ASCII-encoded hexadecimal file.println(x, OCT); // print as an ASCII-encoded octal file.println(x, BIN); // print as an ASCII-encoded binary file.close(); } else { Serial.print("SD Card: error on opening file arduino.txt"); } } void loop() { }

The content of arduino.txt file:

N 1.23 1.2346 1.23456 1.234560 77 77 4D 115 1001101


Arduino UNO R3
Arduino Starter Kit
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