Weird RTC DS3231 Output only when saving the dates to variables

Question

I am sorry to ask this question as I think it has more to do with my mediocre C++ programming skill than with the arduino. I do have a project where I want to use an RTC DS2131. I started out by using all the separate examples of the modules I need and put them together. But the RTC give me a headache :-(

The example ran fine where it just output the date to the serial port. Somthing along this:

Serial.print(RTC.getDay());
Serial.print("-");
Serial.print(RTC.getMonth());

Now I want these values in different variables because I want to save them on an SD card as well.

Thus I came up with this simple test program:

#include <Wire.h>
#include <RTC.h>
static DS3231 RTC;
void setup()
{ 
 Serial.begin(9600);
 RTC.begin();
}
void loop()
{ 
int yearNow; 
int monthNow, dateNow, hourNow, minuteNow, secondNow, weekNow;
if (RTC.isRunning())
 {
 yearNow=RTC.getYear();
 monthNow =RTC.getMonth();
 dateNow=RTC.getDay();
 weekNow=RTC.getWeek();
 hourNow=RTC.getHours();
 minuteNow=RTC.getMinutes();
 secondNow=RTC.getSeconds();
 
 Serial.print("Weekday: ");
 Serial.print(weekNow);
 Serial.print(' Time:');
 // Finally the hour, minute, and second
 Serial.print(hourNow);
 Serial.print('-');
 Serial.print(minuteNow);
 Serial.print('-');
 Serial.print(secondNow);
 Serial.print(" ## "); 
 Serial.print("Date: ");
 Serial.print(yearNow);
 Serial.print('/');
 Serial.print(monthNow);
 Serial.print('/');
 Serial.println(dateNow);
 
 }
}

Now I would expect this output: Weekday: 4 Time:16-10-36 ## Date: 2020年7月28日

But this is what I get: Weekday: 42591416-10-36 ## Date: 2020年7月28日

As a sidenote the variables in this sketch are declared as "int". After having looked into the header files of the library I tried uint8_t resp. uint16_t for the year. But nothing changed.

I am sorry but I have no clue as what beginner mistake I am achieving this time?? :-(

Thanks for your help.

Answer 1

You used single quotes instead of double quotes. Single quotes are for single characters. Double quotes are for strings (or character arrays).

Serial.print(' Time:');

should be

Serial.print(" Time:");

• Andreas K.: Thanks. I thought " and ' are interchangable.
• Gerben: They are in javascript or PHP, not in C/C++.