#include <SD.h>
#include <SPI.h>
File myFile;
char fileName[] = "sample.txt";
const int chipSelect = 10;
char charRead;
//char SampleText[] = "Hello World";

void setup()
{
  Serial.begin(9600);
   if (SD.begin(chipSelect))
    {
    Serial.println("SD card is present & ready");
    } 
    else
    {
    Serial.println("SD card missing or failure");
    }
}

void loop() 
{
  char ReceiveArray[20]="";

  Serial.println("Enter a string less than 6 bytes");
  
      
      Serial.println();
    for(int k = 0; k < 7; k++) {
        while ((Serial.available())==0);
        charRead = tolower(Serial.read());  //force ucase
       // Serial.write(charRead); //write it back to Serial window

       if (charRead == '\n') //end of line (or 10)
   {
      exit;
   }
else
        ReceiveArray[k] = charRead;
    }
myFile = SD.open(fileName, FILE_WRITE);
  if (myFile) // it opened OK
    {
    Serial.println("Writing to sample.txt");
    myFile.println(ReceiveArray);
    myFile.close(); 
    Serial.println("Done");
    }
  else 
    Serial.println("Error opening sample.txt");


    delay (1000);
     readFromFile();   //read
     delay (1000);

if (SD.exists(fileName)) 
    {
   Serial.println("Removing sample.txt");
    SD.remove(fileName);
  
}
}
void readFromFile()
{
 byte i=0; //counter
  char inputString[100]; //string to hold read string
  
  //now read it back and show on Serial monitor 
  // Check to see if the file exists:
  if (!SD.exists(fileName)) 
      Serial.println("sample.txt doesn't exist."); 
  Serial.println("Reading from sample.txt:");
  myFile = SD.open(fileName);

  while (myFile.available()) 
  {   
   char inputChar = myFile.read(); // Gets one byte from serial buffer
    if (inputChar == '\n') //end of line (or 10)
    {
      inputString[i] = 0;  //terminate the string correctly
      Serial.println(inputString);
      i=0;
    }
    else
    {
      inputString[i] = inputChar; // Store it
      i++; // Increment where to write next
      if(i> sizeof(inputString))
        {
        Serial.println("Incoming string longer than array allows");
        Serial.println(sizeof(inputString));
        while(1);
        }
    }
  }
 }