String Constants

MIOS programming (C)
1

I’m at work right now and I wanted to ask about a problem I had this morning.

I’m defining my pot config in structs like so.

typedef struct s_pots {

const unsigned char description[16];

const unsigned char param1;

const unsigned char type;

<etc..>

} pots;

const pots PotConfiguration[32] {

//description      param1    type    <etc…>

{“12345678abcdefgh”, 16, 2, <etc…>},

{“12345678abcdefgh”, 15, 2, <etc…>},

};

Later, the description is being passed onto MIOS_LCD_PrintCString() like so.

MIOS_LCD_PrintCString(PotConfiguration[pin].description);

I get an error when compiling for the ‘description’ const having too many elements.

the error goes away if I define description with 17 elements like so:

const unsigned char description[17];

I’m using a 2x16 LCD screen and it seems I should define the descriptions as being 16 in length.

I wipped out my old ‘C’ book and it looks like strings should have an additionalnull terminator. The book showed this: ‘\0’.

Is this my problem? Do I need to make my description one extra char longer? And if I do, how do I pass a null or ‘\0’ at the end of the string in my config above?

Thanks for everything… again.

2

I wipped out my old ‘C’ book and it looks like strings should have an additionalnull terminator. The book showed this: ‘\0’.

Is this my problem?

Do I need to make my description one extra char longer?

I think so, yes.

And if I do, how do I pass a null or ‘\0’ at the end of the string in my config above?

No, this should be done automatically for you, when you use double-quotes (").

Best regards,

Michael

3

Just to chime in with the post above, yeah.  you need to allocate an extra byte for the null termination of the string, so 17 works but 16 won’t.

4

Thanks.

I was worried that by declaring it [17] I was just hacking a solution… which is not what I wanted to do.

5

This is how you know you’ve got too much on your mind… I just clicked reply to mention the 256 element limitation on arrays…

…which we already fixed up ages ago…and I personally documented on the wiki… ::)OMG I’m going crazy… hahahah this is what computers will do to you!!

Just a little light entertainment at my own expense :slight_smile: Keeping on topic, you could always try making the string 15 chars long :slight_smile: