String handling help appreciated

Forum 2005-2010 (read only) Software Syntax & Programs
1

I want to be able to send variable text strings to an LCD. I want to put the text in a variable then call the LCD handler function I am creating. I have done this thus far

char LCDMessage[200] = " "; //allocate space for 200 characters

Later in various places where I want to call the LCD handler I do the following

strcpy(LCDMessage, "some text")

then call the LCD handler which does the following (among other things)

Serial.print(LCDMessage)

All of this works fine but I would love to have the available space I have allocated to LCDMessage be variable. Perhaps I define it to be 200 characters and then inadvertently send 205 characters...oops!

Is there a way to make this more dynamic? Am I going about the string handling in the right way to begin with?

Thanks,

Jim, K6JMG

2

What about passing your message string to the lcdhandler as an argument.

3

If you want to set up the string in one place and then use it in another, why not use a pointer? For example:

char **lcd_message;

char my_message[] = "Hola, mundo";

*lcd_message = "Hello, world";
display_message();
*lcd_message = my_message;
display_message();
...
void display_message(void)
{
Serial.print(*lcd_message);
}
4

Why have a display_message function that relies on a global variable?

Better would be:

void display_message(char *theMessage)
{
    Serial.print(theMessage); // or LCD.print(theMessage);
}

Then call it:

char my_message[] = "Hola, mundo";
display_message(my_message);

display_message("Print this, you LCD!");