   }
 }
 
+void checkCard(){
+  boolean flag = SD.exists("twitter.txt");
+  if(flag){
+    Serial.println("File exists");
+  }else{
+    Serial.println("File does not exist");
+  }
+}
+
 void read(){
-  File dataFile = SD.open("b_binary.txt");
+  File dataFile = SD.open("twitter.txt");
   if(!dataFile){
     Serial.println("Error on opening the file");
     return;

//CS pin for Arduino Uno
const int chipSelect = 8;
//const int chipSelect = 4; //for Ethernet shield
const int imageWidthBytes = 8;
const int lineWidth = 65;

void setup() {
  // put your setup code here, to run once:

}

void convertToByte(){
  File dataFile = SD.open("twitter.txt");
  if(!dataFile){
    Serial.println("Error on opening the file");
    return;
