TFT LCD screen .text() method not working?

Projects Programming
1

So I recently got started with Arduino and decided to do something with the LCD screen.
Apparently I cannot use a variable in the .text() method?

Works:

#include <TFT.h> // Hardware-specific library
#include <SPI.h>

#define CS   10
#define DC   9
#define RESET  8

TFT lcd = TFT(CS, DC, RESET);

void setup() {
  lcd.background(255, 255, 255);
  lcd.stroke(0, 0, 0);
  lcd.setTextSize(5);
  lcd.text("fdsa", 10, 20);
}
void loop() {
}

Does not work:

#include <TFT.h> // Hardware-specific library
#include <SPI.h>

#define CS   10
#define DC   9
#define RESET  8
String fdsa = "fdsa";

TFT lcd = TFT(CS, DC, RESET);

void setup() {
  lcd.background(255, 255, 255);
  lcd.stroke(0, 0, 0);
  lcd.setTextSize(5);
  lcd.text(fdsa, 10, 20);
}
void loop() {
}

Which returns error messages:
Arduino: 1.8.4 (Windows 10), Board: "Arduino/Genuino Uno"

In file included from C:\Program Files (x86)\Arduino\libraries\TFT\src/TFT.h:36:0,

from C:\Users\Jason\Documents\Arduino\TFTPractice2\TFTPractice2.ino:1:

C:\Program Files (x86)\Arduino\libraries\TFT\src/utility/Adafruit_GFX.h:60:3: warning: #warning "The SD library was not found. loadImage() and image() won't be supported." [-Wcpp]

#warning "The SD library was not found. loadImage() and image() won't be supported."

^

C:\Users\Jason\Documents\Arduino\TFTPractice2\TFTPractice2.ino: In function 'void setup()':

TFTPractice2:15: error: no matching function for call to 'TFT::text(String&, int, int)'

lcd.text(fdsa, 10, 20);

^

C:\Users\Jason\Documents\Arduino\TFTPractice2\TFTPractice2.ino:15:24: note: candidate is:

In file included from C:\Program Files (x86)\Arduino\libraries\TFT\src/TFT.h:36:0,

from C:\Users\Jason\Documents\Arduino\TFTPractice2\TFTPractice2.ino:1:

C:\Program Files (x86)\Arduino\libraries\TFT\src/utility/Adafruit_GFX.h:174:2: note: void Adafruit_GFX::text(const char*, int16_t, int16_t)

text(const char * text, int16_t x, int16_t y),

^

C:\Program Files (x86)\Arduino\libraries\TFT\src/utility/Adafruit_GFX.h:174:2: note: no known conversion for argument 1 from 'String' to 'const char*'

exit status 1
no matching function for call to 'TFT::text(String&, int, int)'

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

The only difference is that I stored the string "fdsa" in variable fdsa. Can someone explain??

2

Apparently I cannot use a variable in the .text() method?

Nonsense.

The only difference is that I stored the string "fdsa" in variable fdsa. Can someone explain??

The problem is that you stored the string "fsda" in a String variable, NOT a string (NULL terminated array of chars). Forget that the stupid String class even exists.

3

Ok, thanks for your help.
I'm more familiar with Java, so some of these subtle differences really trip me up.
So I should use data type char?

4

So I should use data type char?

You need an array of chars. Be sure to NULL terminate the array.