How do you save SD card read() values?

Other Hardware Storage
1

Hello,
I am working on a project that requires me to retrieve saved data from an SD card and saving that data into a variable (most likely a character array or String). I need some guidance on how to achieve this.

Here is a sample of my code
Any help is appreciated

  myFile = SD.open(profile, FILE_READ);
  while(myFile.available()){
   Serial.write(myFile.read()); // I dont want to write to monitor I want to save these characters
  }

Any help is appreciated

2

Why are you using Serial.write ?

3

I used it to illustrate exactly what I don't want to do. I don't want to write to the serial monitor, I want to save what I read instead.

4

I think you need to understand how to use myFile.read( ) function .
What does it do?
Do you know?

5

To my understanding, it returns the next character in the array

6

Not an array, but I think it's called a stream, and as such you can use any of the techniques from the Stream class which means Serial.

So for example in the sketch below, parseFloat() (clue's in the name :wink: ) parses some floats out of an SD card stream. (Not actually advocating the use of parsefloat() since it blocks afaik, but you get the idea.)

/*
  BASED ON SD card file dump

  This example shows how to read a file from the SD card using the
  SD library and send it over the serial port.

  The circuit:
   SD card attached to SPI bus as follows:
 ** MOSI - pin 11
 ** MISO - pin 12
 ** CLK - pin 13
 ** CS - pin 4 (for MKRZero SD: SDCARD_SS_PIN)

  created  22 December 2010
  by Limor Fried
  modified 9 Apr 2012
  by Tom Igoe

  This example code is in the public domain.

*/

#include <SPI.h>
#include <SD.h>
const int chipSelect = 4;

float myVar1;
float myVar2;
float myVar3;
float myVar4;

void setup()
{
  Serial.begin(9600);
 
  Serial.print("Initializing SD card...");

  // see if the card is present and can be initialized:
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    // don't do anything more:
    return;
  }
  Serial.println("card initialized.");

  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  File dataFile = SD.open("floats.txt"); //<<<<<<<<<<<<<<<<<<<<<< set file name here

  // if the file is available, read from it:
  if (dataFile)
  {
    while (dataFile.available())
    {
      //parse the next 4 values out of the file:
      myVar1 = dataFile.parseFloat();
      myVar2 = dataFile.parseFloat();
      myVar3 = dataFile.parseFloat();
      myVar4 = dataFile.parseFloat();
      //print them to the monitor:
      Serial.println(myVar1);
      Serial.println(myVar2);
      Serial.println(myVar3);
      Serial.println(myVar4);

      delay(1000);
      //go back to the top for the next line...
    }//while data available
    //or ....
    Serial.println(".... no more data");
    dataFile.close();
  }// if datafile
  // if the file isn't open, pop up an error:
  else {
    Serial.println("error opening the data file");
  }
}//setup

void loop()
{
}

As far as I know you can use any Serial technique to read an SD card; Robin2's serial tutorial might help.