rewindDirectory() will bring you back to the first file in the directory, used in conjunction with openNextFile().

file.rewindDirectory()

file: an instance of the File class.

None

#include <SD.h>
 
File root;
 
void setup()
{
  Serial.begin(9600);
  pinMode(10, OUTPUT);
 
  SD.begin(10);
 
  root = SD.open("/");
 
  printDirectory(root, 0);
 
  Serial.println("done!");
}
 
void loop()
{
  // nothing happens after setup finishes.
}
 
void printDirectory(File dir, int numTabs) {
   while(true) {
 
     File entry =  dir.openNextFile();
     if (! entry) {
       // no more files
       // return to the first file in the directory
       dir.rewindDirectory();
       break;
     }
     for (uint8_t i=0; i<numTabs; i++) {
       Serial.print('\t');
     }
     Serial.print(entry.name());
     if (entry.isDirectory()) {
       Serial.println("/");
       printDirectory(entry, numTabs+1);
     } else {
       // files have sizes, directories do not
       Serial.print("\t\t");
       Serial.println(entry.size(), DEC);
     }
   }
}

• open()
• openNextFile()
• isDirectory()

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