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Hello I am using the u8glib library to draw text on the string but it keeps giving me an error with the string

 String name1 = "";
 ...
 void draw(){
  u8g.setFont(u8g_font_micro);
  u8g.drawStr(22, 37, name1);
 }

why dosnt this work?

Here is the error:

C:\Program Files (x86)\Arduino\libraries\U8glib/U8glib.h:200:16: note: no known conversion for argument 3 from 'int' to 'const __FlashStringHelper*' no matching function for call to 'U8GLIB_PCD8544::drawStr(int, int, String&)'

user3704293
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user2279603
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2 Answers2

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String is evil and should be avoided at all costs (http://hacking.majenko.co.uk/the-evils-of-arduino-strings)

The author of u8glib knows that and has refused (quite rightly) to implement them.

You should not use String either. If you really must for some obscure reason then you will have to pass the internal "C string" reference to the drawStr function instead of the whole String object:

u8g.drawStr(22, 37, name1.c_str());

The only reason people use String is because they are too lazy to learn the proper way of handling textual data in C.

Majenko
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  • The link is broken: *"Hmm. We’re having trouble finding that site. We can’t connect to the server at hacking.majenko.co.uk."* – Peter Mortensen Feb 06 '23 at 03:48
  • Re *"String is evil"*: I have come to the same conclusion, after some pain. It was there all along, but it didn't really show up until now. It was used in formatting of error reporting going to the serial port and as the frequency of (spurious, harmless) errors increased due to some changes to the system, occasional hard freezes was the result. Strangely, it was dependent on the Serial Monitor (or another terminal, like [Screen](https://en.wikipedia.org/wiki/GNU_Screen)) being open/connected... It being open made the error nearly 100% reproducible. – Peter Mortensen Feb 06 '23 at 03:55
  • cont' - That was with an [Arduino Leonardo](https://store.arduino.cc/arduino-leonardo-with-headers). – Peter Mortensen Feb 06 '23 at 04:01
  • If they shouldn't use String, what should they use instead? Perhaps add something to this effect to the answer? And/or a reference to [this answer](https://arduino.stackexchange.com/questions/86250/). – Peter Mortensen Feb 06 '23 at 04:02
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Like the documentation says, that method doesn't take a String object. Call the c_str() method of the String object and pass that instead.

Ignacio Vazquez-Abrams
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