[SD] How can I read a file into a folder

Other Hardware Storage
1

Good evening,

I can write and save data into a folder structure of my SD card.

Actually, I am trying to read a file.
As long as the file is at the roor, I can do it, but I can not specify a folder path.

For exemple, I am trying to read that files

/2015/12/25/14-20-20.TXT

and

/14-20-20.TXT

With the following code, I can read the file which is at the root

char param[170];
sd_read(NULL, param); // I set temporarely NULL and I set the path in the fonction
SerialUSB.println(param);
void sd_read(char * fileName, char * param)
{
  int i =0;
 if(isSdReady == true)
 {
  char buff[PARAMSIZE];
  memset(param, '\0', PARAMSIZE);
  
  #ifdef LOGGER
    if(isSdReady == true)
    {
 
      logfile = SD.open("/14-20-20.TXT");


      
      if (logfile)
      {
        
        while(logfile.available())
        {
          //SerialUSB.write(logfile.read());

          if(i < PARAMSIZE)
          {
            param[i++] = logfile.read();
          }
          else
          {
            sprint(F("OF param: "),0); sprintln(i,0);
          }
      
        }
        param[i]='\0';
        
        logfile.close();
      }
      // if the file isn't open, pop up an error:
      else
      {
        sprint(F("error opening "),2);
        sprintln(fileName,2);
      }
    }
  #endif
 }
}

This work, but now if I specify folders, it return me "Error opening". (The file exists )

char param[170];
sd_read(NULL, param); // I set temporarely NULL and I set the path in the fonction
SerialUSB.println(param);
void sd_read(char * fileName, char * param)
{
  int i =0;
 if(isSdReady == true)
 {
  char buff[PARAMSIZE];
  memset(param, '\0', PARAMSIZE);
  
  #ifdef LOGGER
    if(isSdReady == true)
    {
 
      logfile = SD.open("/2015/12/25/14-20-20.TXT");


      
      if (logfile)
      {
        
        while(logfile.available())
        {
          //SerialUSB.write(logfile.read());

          if(i < PARAMSIZE)
          {
            param[i++] = logfile.read();
          }
          else
          {
            sprint(F("OF param: "),0); sprintln(i,0);
          }
      
        }
        param[i]='\0';
        
        logfile.close();
      }
      // if the file isn't open, pop up an error:
      else
      {
        sprint(F("error opening "),2);
        sprintln(fileName,2);
      }
    }
  #endif
 }
}

How can I go to directorie and read my files?
Is there a cd command?

Thank for your help and happy christmas!

2

I open a file within a folder like this. (Without the leading forward slash that you used.):-

// Open the "SDFile3.txt" file inside the "SDDir1" folder:-
sdFile3 = SD.open(F("SDDir1/SDFile3.txt"));     // Open for reading only.

(The SDDir1 folder is located in the root of the card.)