Reading line by line in Arduino IDE-CodePudding

I'm trying to read txt file (has numeric values) line by line. I used SPIFFS and I used this function

void readFile(fs::FS &fs, const char * path){
   Serial.printf("Reading file: %s\r\n", path);

   File file = fs.open(path);
   if(!file || file.isDirectory()){
       Serial.println("− failed to open file for reading");
       return;
   }
   
   int count = 0;
   Serial.println(" read from file:");

   while(file.available()){
    if (count < 100)  
      Serial.write(file.read());  
   } 
}

What is the alternative function for "file.read()" something like "readline" because I need to read the file from first line to 100 and from 101 to 200 and so on .

CodePudding user response：

To read lines from Serial, network Client, from File or other object implementing the Arduino Stream class you can use function readBytesUntil.

uint8_t lineBuffer[64];
while (file.available()) {
  int length = file.readBytesUntil('\n', lineBuffer, sizeof(lineBuffer) - 1);
  if (length > 0 && lineBuffer[length - 1] == '\r') {
    length--; // to remove \r if it is there
  }
  lineBuffer[length] = 0; // terminate the string
  Serial.println(lineBuffer);
}

CodePudding user response：

The File is a Stream and has all of the methods that a Stream does, including readBytesUntil and readStringUntil.