#include "U8glib.h"

const char err[] PROGMEM = {"1234"};
char msg[] = {"abcd"};
char msg2[4];

U8GLIB_SSD1306_128X64 u8g; // create an instant of OLED display
int i2=0;
void setup() {
  Serial.begin(9600);
  Serial.println("test");
  Serial.println(msg);

      for (byte i = 0; i < strlen(err); i++) {
        // we need to recall each char one byte at a time, and 
        // use the i as an incrementer to get each new byte in a sequence
        char c = pgm_read_byte_near(err + i);
        msg2[i]=c;
        Serial.println(c);
    }
    Serial.println(msg2);
  u8g.setFont(u8g_font_7x13); // set the font for text
  //u8g.setColorIndex(1); set the display colour can be done outside picture loop
}

int x = 0;
void loop() {

  if (x < 108){
    x = x + 6;
    
  }else{
    x = 0;
  }

  u8g.setColorIndex(1); // set the colour to white
  u8g.drawStr(0, 50, "hello");

  u8g.firstPage(); //marks the beginning of the picture loop.
  do {
    u8g.setColorIndex(1); // set the colour to white
    
    u8g.drawStr(i2, 50, "Christian"); //display "hello world" text (0,50) 
    u8g.drawStr(i2, 10, "123456789");
    u8g.drawStr(i2, 24, msg);
     u8g.drawStr(i2, 30, msg2);
    
    i2=i2+1;

    delay(100);


    //note (X,Y) position is the lower left corner of the first character of the string
    
  //  u8g.drawStr(0, 5, "hello world"); //Y position = 5 < height of texts so cant see the text fully. 
    
   // u8g.drawFrame(0, 10, 128, 20); //draw frame at (0,10) with width = 128, height = 20
    
  //  u8g.drawBox(10, 15, x, 10); //draw box at (10,15) with width = x, height = 10

    //in drawBox and drawFrame, (X,Y) position is upper left edge

 //   u8g.drawCircle(110,50,10); // draw circle with centre at (110,50) and radius = 20

    u8g.setColorIndex(0); //change the colour back to black
    
    u8g.drawPixel(15,18); //update the colour of pixel at (15,18) to black colour
  } while ( u8g.nextPage() ); //marks the end of the body of the picture loop

  u8g.setColorIndex(1);
  u8g.drawStr(0, 20, "outside"); 
  //drawing function must use inside the picture loop.
}