How to get numbers from sd card? - arduino

Question

I am bad at coding. I have a file called Test.cal in sd card contained 6 numbers. 20,21,22,23,24,25
But I do not know how to get this six number. Can someone help me ? Below is my own thought about the coding.
#include <SD.h>
float meterTemp[6];
String theLines[15];
File myFile;
void setup()
{
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
Serial.print("Initializing SD card...");
// On the Ethernet Shield, CS is pin 4. It's set as an output by default.
// Note that even if it's not used as the CS pin, the hardware SS pin
// (10 on most Arduino boards, 53 on the Mega) must be left as an output
// or the SD library functions will not work.
pinMode(53, OUTPUT);
if (!SD.begin(4)) {
Serial.println("initialization failed!");
return;
}
Serial.println("initialization done.");
// re-open the file for reading:
myFile = SD.open("Test.cal");
if (myFile) {
//I want to put the file numbers into array, meterTemp[6], not inclduing comma, so when I get meterTemp[0]=-32, and so on.
// read from the file until there's nothing else in it:
while (myFile.available()) {
Serial.write(myFile.read());
}
// close the file:
myFile.close();
} else {
// if the file didn't open, print an error:
Serial.println("error opening test.txt");
}
}
void loop()
{
// nothing happens after setup
}

Answer 1

#include <SD.h>
float meterTemp[6];
String theLines;
File myFile;
String filename="Test.cal";
int line=0;
void setup()
{
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
Serial.print("Initializing SD card...");
// On the Ethernet Shield, CS is pin 4. It's set as an output by default.
// Note that even if it's not used as the CS pin, the hardware SS pin
// (10 on most Arduino boards, 53 on the Mega) must be left as an output
// or the SD library functions will not work.
pinMode(53, OUTPUT);
if (!SD.begin(4)) {
Serial.println("initialization failed!");
return;
}
Serial.println("initialization done.");
// re-open the file for reading:
myFile = SD.open("Test.cal");
if (myFile) {
Serial.println("test.txt:");
;
// read from the file until there's nothing else in it:
while (myFile.available()) {
Serial.write(myFile.read());
theLines=readFile(filename,line);
Serial.println(theLines);
}
// close the file:
myFile.close();
} else {
// if the file didn't open, print an error:
Serial.println("error opening test.txt");
}
}
void loop()
{
// nothing happens after setup
}
String readFile(String filename, int line)
{
char s[20];
char FileName[sizeof(filename)];
filename.toCharArray(FileName, sizeof(FileName));
File myFile = SD.open(FileName,FILE_READ);
if(myFile)
{
String recived = "";
int cur = 0;
char ch;
while (myFile.available())
{
ch = myFile.read();
if(ch == ',')
{
cur++;
if(cur == line)
{
myFile.close();
return String(recived);
}
}
else
{
recived += ch;
}
}
}
return "";
}

Answer 2

String readFile(String filename, int line)
{
char FileName[sizeof(filename)];
filename.toCharArray(FileName, sizeof(FileName));
File myFile = SD.open(FileName,FILE_READ);
if(myFile)
{
String recived = "";
int cur = 0;
char ch;
while (myFile.available())
{
ch = myFile.read();
if(ch == '\n')
{
cur++;
if(cur == line)
{
myFile.close();
return String(recived);
}
}
else
{
recived += ch;
}
}
}
return "";
}
It is from Arduino Visual code generator.Replace "\n" with your char