Create variable directory and incremetal files

Using Arduino Storage
1

Hello everybody!
I'm doing a project where i need to collect data from sensors and then save these data in a SD card memory; all these things are well explained in Arduino's reference guide on the website but I however found a trouble: since in my project i collect the temperature and other parameters per each day, I also need to collect them in order into the SD, making a txt file per each day. it would be beautiful if I can also make a folder for each year, with a folder for each month in it, like this: 2013/jan,feb,mar,apr,may,jun..etc and for each month 31 or 30 files(one per day).
The trouble is that in the code line for writing a directory and also for making files, you must write only const char : SD.mkdir("a/b/c") in this i'll have only three folders; SD.open("*.txt")
My question is: how I can use for example a for loop for increasing (for example an array, year[X]), for creating a new directory every year, and the same for month of course?

thanks for answering, and if this topic had already been treated, can you send me to that page?
thanks a lot.

2

The trouble is that in the code line for writing a directory and also for making files, you must write only const char : SD.mkdir("a/b/c") in this i'll have only three folders;

That is not true. You can create any number of directory levels at once, using a dynamically defined string.

int year = 2013;
char dirName[24];
sprintf(dirName, "%d/Jan", year);
SD.mkdir((const char *)dirName);

should create a directory called Jan in one called 2013.

My question is: how I can use for example a for loop for increasing (for example an array, year[X]), for creating a new directory every year, and the same for month of course?

Why would year be an array? In the snippet about, you can increment year by 1 and get 2014/Jan created.

You could create an array of month names:
char monthNames[] = {"", "Jan", "Feb", "Mar", "Apr", ...

Then:

int month = 3;
sprintf(dirName, "%d/%s", year, monthNames[month]);
SD.mkdir((const char *)dirName);

should create a directory called Mar in one called 2013.

3

@PaulS:
Thank you very much for the help, and I'm sorry for having written false things but I really didn't know that kind of code, I studied it at high school (C++), but not in a close way, so I really thank you for help, this will allow me to finish my project and do more complex project in future!

4

@PaulS
Hi and thanks again for the help, I have other questions:
when i compile the code line you have given to me, at: char monthNames[] = {"", "Jan", "Feb", "Mar", "Apr"}; the compiler says:

error: too many initializers for 'char []'

and for: SD.mkdir((const char )dirName); error: invalid conversion from 'const char' to 'char*'

then I don't know if there are other errors

I put this code lines in a program just to try..

5 
char monthNames[] = {"", "Jan", "Feb", "Mar", "Apr"}; the compiler says:

should have been:

char *monthNames[] = {"", "Jan", "Feb", "Mar", "Apr"}; the compiler says:

and for: SD.mkdir((const char )dirName); error: invalid conversion from 'const char' to 'char*'

Then, the cast is not necessary.

SD.mkdir(dirName);
6

@PaulS, hello, since you have been able to help me i ask again for your help, this time i would need to know how write a file into a directory I have created before. the trouble is I have created the directory and the file with the code lines you have shown me in messages before, but when I try to create the files in the directory, i fail.

my idea is: I create a directory that it can change when i decide to do that, and i would make a file per day, and then write on time every minute. Thanks again for your time!!

I post you the skecth:

#include <SD.h>
char dirName[8],DATO[18],fileName[8],DataString[20];
unsigned long ms=0, psd=0;
int anno=2014;
byte mese=1, giorno=2, ore=3, minu=4, sec=5;
File myFile;

void setup(){
Serial.begin(9600);
Serial.print("Initializing SD card...");
pinMode(10, OUTPUT);

if (!SD.begin(4)) {
Serial.println("initialization failed!");
}
Serial.println("initialization done.");

}

void loop(){

Serial.println("sd");

sprintf(dirName, "%d/%d/%d.txt", anno,mese,giorno); //per creare la directory
//SD.mkdir(dirName);
//sprintf(fileName,"%d.txt",giorno);// per creare il nome del file
//sprintf(DATO,"%d/%d",dirName,fileName);//per creare la location dove scrivere il file
sprintf(DataString,"%d/%d/%d %d:%d:%d ",giorno,mese,anno,ore,minu,sec);// crea la stringa da stampare su sd

myFile = SD.open(dirName);
myFile = SD.open(dirName, FILE_WRITE);
myFile.println(DataString);
if (myFile) {
Serial.print("Writing to test.txt...");
myFile.println(DataString);
//myFile.print(T,1);
//myFile.print(" , ");
//myFile.print(H);
//myFile.print(" , ");
//myFile.print(P);
//myFile.print(" , ");
//myFile.println(A);

// close the file:
myFile.close();
Serial.println("done.");
} else {
// if the file didn't open, print an error:
Serial.println("error opening test.txt");
}
giorno++;
ore++;
minu++;
sec++;

delay(1000);

}