Printing a substring

Projects Programming
1

I have a constant string defined as follows:

char* room_text[] = {
"Office.",
"Den....",
"MBath...",
"Evap...",
"Roof...",
"FirePl.",
"HVAC...",
"Utility",
"Gym....",
"W Bed..",
"E Bed..",
"Lab...",
"Air Fan" } ;

How do I print [to an LCD] a substring of seven characters from this character string? I could use a crowbar and concatenate seven bytes from this string into a new string, then print that, but I'm sure there is a more elegant way. Thanks.

2

I'm having a little difficulty understanding what you want to accomplish, so could you provide an example?

3

Maybe I'm misunderstanding, but this works:

void setup() {
  int i;
  // put your setup code here, to run once:
  Serial.begin(9600);
  
  char* room_text[] = {
  "Office.",
  "Den....",
  "MBath...",
  "Evap...",
  "Roof...",
  "FirePl.",
  "HVAC...",
  "Utility",
  "Gym....",
  "W Bed..",
  "E Bed..",
  "Lab...",
  "Air Fan" } ;

  for (i = 0; i < sizeof(room_text) / sizeof(room_text[0]); i++) {
    Serial.println(room_text[i]);
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}

Just change the Serial object to your LCD object.

4

I have a constant string defined as follows:

That is NOT a constant string. It is an array of strings that are NOT constant.

5

PaulS, you hit it pretty close to the head. It is an array, but in this case it won't change. Can it be declared as a constant so that it doesn't take up RAM?

I didn't understand the array, so I was treating it as a long string and trying to cut a substring out of it.

The following code prints the 7 characters with no other manipulation required:

lcd.print(room_text[ (Unit_ID - 1) ]) ;

My other "discovery" is that I don't have to have constant length text phrases--the commas establish the array index.