How to convert char array to String in arduino?

Question

I want to convert const char array in PROGMEM to String. How do I do this?

const char charArray[] PROGMEM = "Some text";

• Tri: If you mean a C++ style string, I think you just need to do this - stackoverflow.com/questions/8960087/…
• Mohamad_Frm: No, I want to convert this in Arduino-IDE. That is not work correctly!
• Tri: I just saw the answer and I had no idea that was even possible. I think that is your answer.
• Mohamad_Frm: Unfortunately that is not work. Thank you, however.
• jsotola: what does this mean? that is not work .... that statement provides no useful information .... describing the actual error would help

Answer 1

you can use a cast to __FlashStringHelper to invoke the right constructor of the String class. It is the constructor which copies the char array from PROGMEM. __FlashStringHelper is intended as return type for the F() macro.

const char charArray[] PROGMEM = "Some text";
void setup() {
 Serial.begin(115200);
 String s((const __FlashStringHelper*) charArray);
 Serial.println(s);
}
void loop() {
}

• Mohamad_Frm: That is right, but how do this in loop or another functions?
• Juraj: PROGMEM is always global. and setup() is a function like every other so same way
• Mohamad_Frm: Absolutely, but when I write this code in loop, the compiler will generate this error: conflicting declaration 'String s'
• Mohamad_Frm: Thanks so much. The compiler error was due to another part of my sketch.