Read CSV or TXT from SD card into string or array

Using Arduino Storage
19

fat16lib:
Here is a simple sketch that reads a CSV file with two numbers on each line. It doesn't use the dangerous String class.

#include <SD.h>

File file;

bool readLine(File &f, char* line, size_t maxLen) {
  for (size_t n = 0; n < maxLen; n++) {
    int c = f.read();
    if ( c < 0 && n == 0) return false;  // EOF
    if (c < 0 || c == '\n') {
      line[n] = 0;
      return true;
    }
    line[n] = c;
  }
  return false; // line too long
}

bool readVals(long* v1, long* v2) {
  char line[40], *ptr, *str;
  if (!readLine(file, line, sizeof(line))) {
    return false;  // EOF or too long
  }
  *v1 = strtol(line, &ptr, 10);
  if (ptr == line) return false;  // bad number if equal
  while (*ptr) {
    if (*ptr++ == ',') break;
  }
  *v2 = strtol(ptr, &str, 10);
  return str != ptr;  // true if number found
}

void setup(){
  long x, y;
  Serial.begin(9600);
  if (!SD.begin(SS)) {
    Serial.println("begin error");
    return;
  }
  file = SD.open("TEST.CSV", FILE_READ);
  if (!file) {
    Serial.println("open error");
    return;
  }
  while (readVals(&x, &y)) {
    Serial.print("x: ");
    Serial.println(x);
    Serial.print("y: ");
    Serial.println(y);
    Serial.println();
  }
  Serial.println("Done");
}
void loop() {}




Reading this "TEST.CSV" file.
Results in this output

fat16lib:
Here is a simple sketch that reads a CSV file with two numbers on each line. It doesn't use the dangerous String class.

#include <SD.h>

File file;

bool readLine(File &f, char* line, size_t maxLen) {
  for (size_t n = 0; n < maxLen; n++) {
    int c = f.read();
    if ( c < 0 && n == 0) return false;  // EOF
    if (c < 0 || c == '\n') {
      line[n] = 0;
      return true;
    }
    line[n] = c;
  }
  return false; // line too long
}

bool readVals(long* v1, long* v2) {
  char line[40], *ptr, *str;
  if (!readLine(file, line, sizeof(line))) {
    return false;  // EOF or too long
  }
  *v1 = strtol(line, &ptr, 10);
  if (ptr == line) return false;  // bad number if equal
  while (*ptr) {
    if (*ptr++ == ',') break;
  }
  *v2 = strtol(ptr, &str, 10);
  return str != ptr;  // true if number found
}

void setup(){
  long x, y;
  Serial.begin(9600);
  if (!SD.begin(SS)) {
    Serial.println("begin error");
    return;
  }
  file = SD.open("TEST.CSV", FILE_READ);
  if (!file) {
    Serial.println("open error");
    return;
  }
  while (readVals(&x, &y)) {
    Serial.print("x: ");
    Serial.println(x);
    Serial.print("y: ");
    Serial.println(y);
    Serial.println();
  }
  Serial.println("Done");
}
void loop() {}




Reading this "TEST.CSV" file.
Results in this output

@fat16lib, I am having a little difficulty in following your code; however with some time/google I think I will figure it out. If you have a minute, could you look at my post and see if this code you posted would be applicable to my situation? I have an SD card with the fixed-length HEX and then the username, can I use your code for this case?

https://forum.arduino.cc/index.php?topic=622216.0

ba322d387d980d74fc5d0d46, John
ba039b572f612e58d05a8c2d, Katie
979aeeb3ee35360a24d6190, Sandra
78cabc678dc0a503647cb05d, Tim