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Arduino File.readStringUntil()
Description
The File.readStringUntil() function reads characters from a file into a String. The function terminates if the terminator character is detected or it times out (see setTimeout()).
The File.readStringUntil() function inherits from the Stream utility class.
Syntax
file.readStringUntil(terminator)
Parameter Values
- file: an instance of a class that inherits from File.
- terminator: the character to search for. Allowed data types: char.
Return Values
- The entire String read from a file, up to the terminator character
Notes and Warnings
The terminator character is discarded from the return
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.readstringuntil
*/
#include <SD.h>
#define PIN_SPI_CS 4
File file;
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 line_count = 0;
while (file.available()) {
String line = file.readStringUntil('\n'); // \n character is discarded from buffer
line_count++;
Serial.print("Line ");
Serial.print(line_count);
Serial.print(": ");
Serial.println(line);
}
file.close();
} else {
Serial.print(F("SD Card: error on opening file"));
}
}
void loop() {
}
- Open Serial Monitor, you will see as below:
COM6
Line 1: Hi
Line 2: Arduino
Autoscroll
Clear output
9600 baud
Newline
Tutorials
See Also
※ ARDUINO BUY RECOMMENDATION
| Arduino UNO R3 | |
| Arduino Starter Kit |
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