error: invalid conversion from 'uint8_t' to 'const char*'

Hi,

I want to display on LCD 2,4'' current day information like this: "PN 11/11/2015, 13:45"

I am using RTCLib and RTC module DS3231, I have problem with displaying:

 DateTime now = RTC.now(); 
unsigned int dayOfWeek = now.dayOfWeek(); 
    
char* days[8] = {"MO","TU","WE","TH", "FR","SA","SU"};
    
  char * line = "";
  strcat(line,days[dayOfWeek]);
  strcat(line,now.day()); //error: invalid conversion from 'uint8_t' to 'const char*'
    TSC.drawString(line ,  0, 100, 2, WHITE);

How should I convert 'uint8_t' to 'const char*', I am using Arduino IDE 1.5.5 r2

You can use itoa or sprintf.

If you're going to use strcat like that, you need to create a buffer big enough to hold the result. The empty string you start with here can hold zero characters before it overwrites memory it doesn't own and crashes the program.

Thanks for both answers!

I am still having problem with running it.

Serial prints: €ŸöMO2015, MO2015 is ok, but what is before it??

 DateTime now = RTC.now();
  unsigned int dayOfWeek = now.dayOfWeek(); 
      char buffer [10];
    
  char line[70];// = "MO 11/11/2015, 13:45 ";
    
   strcat(line,days[dayOfWeek]);
    itoa (now.year(),buffer,10);
    strcat(line,buffer); 
     
    TSC.drawString(line,  0, 100, 2, WHITE);

Not enough there to tell. Post the rest of the code.

Your "line" variable is uninitialized:

  char line[70];// = "MO 11/11/2015, 13:45 ";

It can and probably does contain junk.