Arduino File.read()
Description
The File.read() function reads a byte or a number of bytes to from the file to buffer.
The File.read() function inherits from the Stream utility class.
Syntax
file.read()
file.read(buf, len)
Parameters
- File: an instance of the File class that is returned by SD.open()
- Buf: an array of characters or bytes
- Len: the number of elements in buf
Returns
- The next byte (or character), or -1 if none is available.
Example Code
- Connect the SD Card to your your PC via an USB 3.0 SD Card Reader
Create a arduino.txt file with the below content
Hi
Arduino
- Connect SD Card to Arduino. See Arduino - Micro SD Card tutorial
- Upload below code to Arduino via Arduino IDE
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/reference/library/arduino-file.read
*/
#include <SD.h>
#define PIN_SPI_CS 4
File file;
char buf[20];
void setup() {
Serial.begin(9600);
if (!SD.begin(PIN_SPI_CS)) {
Serial.println(F("SD CARD FAILED, OR NOT PRESENT!"));
while (1); // don't do anything more:
}
// open file for reading
file = SD.open("arduino.txt", FILE_READ);
if (file) {
int rlen = file.available();
char ch = file.read(); // read the first character
file.read(buf, rlen - 1); // read the remaining to buffer
Serial.print(ch);
Serial.print(buf);
file.close();
} else {
Serial.print(F("SD Card: error on opening file"));
}
}
void loop() {
}
- Open Serial Monitor, you will see as below:
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
Hi
Arduino
Tutorials
See Also
※ ARDUINO BUY RECOMMENDATION
| Arduino UNO R3 | |
| Arduino Starter Kit |
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