How to rotate a string ?

[wedilo]

Hello to all,
I would like to monitor the status of a button via RS232. The character for high (button pressed) should be '-' and for low '_'. So that I can see on the terminal for example: ___-_-_-_-____
But I see : nnnnpnpnpnpnpnnnnn

Please have a look to the code:

[KerryW]

When you define this:

char sLow[2] = "_";
char sHigh[2] = "-";

And use this:
buff[10]=sLow;

you are using the address of sLow, not its value.

Change the definition to:

char sLow = '_';
char sHigh = '-';
And use this:
buff[10]=sLow;

or use
char sLow[2] = "_";
char sHigh[2] = "-";

sLow[0] when you want a '_' character and sHigh[0] when you want a '-' character.

The first one (char sLow = '_'; ) will use less memory.

[wedilo]

Hello KerryW,

I can't understand why, but it works.
Thank you very much

73 Sven

[KerryW]

If you don't understand them, these problems will occur again and again.

Here is a thumbnail sketch of how it works.

char a; // location=0, 1 byte
int b; // location=1, 2 bytes
float c; //location 3, 4 bytes.
char *pa; // location 7, 1 byte
int *pb; // location 8, 1 byte
float *pc; // location 9, 1 byte
char x[2]; // location 10, 2 bytes
int y[2]; // location 12, 4 bytes
float z[2]; // location 16, 8 bytes

a=100; // location 0 contains 100
b=101; // location 1 contains 0, location 2 contains 101
y[0]=0x123; // location 12 contains 0x23, location 13 contains 0x01
pa=&a; // ‘&a’ mean ‘address of a’, or 0. Location 7 contains 0
pb=&y[0]; // location 8 contains 12
pb=y; // a synonym for ‘pb=&y[0]’, location 8 still contains 12.
*pb=102; // ‘*pb’ means ‘the location whose address is in location 8’. Location 8 contains 12, so it puts 0 in 12 and 102 in 13, because the compiler knows that pb points to a 2 byte integer.
pb++; // Location 8 was 12, but since it points to a 2 byte number, the compiler adds 2 instead of 1, so location 8 now contains 14.


If this doesn't do it for you, let me know. It's hard to explain in just a few lines.

[wedilo]

Hello KerryW,
I was surprised about so much information. I will work through your message and will going to understand it completely.
It's hard stuff, but your are right: "it will occur ever and ever"

Thank you very much for your response

73 Sven

[Mark]

KerryW,

CCS is a little different that most compilers:

int b in CCS is 1 byte
long c is 2 bytes
int32 is 4 bytes

Mark

[KerryW]

I'm using something like 2.7?

I don't even have int32, although I knew that the newer ones had it. I wasn't sure how they had implemented if, if they had made int a 16 bit and long a 32, or what. I'm also not sure in they use high byte/low byte or low byte/high byte format. (I knew at one time, but I never remeber such things. If it becomes important, I just take a peek and see)

So many things to forget, and so little time.