How to Declare a string as a constant in SPIN?

william chan

Can a string be declared as a constant or it's impossible?

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www.fd.com.my
www.mercedes.com.my

Praxis

DAT
        strHelloWorld             BYTE "HelloWorld",0

Cheers

william chan

Thanks a million.

P.S. When is your production going to start?

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www.fd.com.my
www.mercedes.com.my

Praxis

Hi William,

We did the OEM design work for that project, the customer will sub the production to production house in Penang.

Cheers

Praxis

PS I forgot to ask, do you stock the new Professional proto board?

william chan

You already expert in Propeller, no need the PPDB.


I tried

serial.str(string(strHelloWorld)) and serial.str(strHelloWorld)

but both cannot send out the string.

What gives?

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www.fd.com.my
www.mercedes.com.my

Praxis

serial.str(@strHelloWorld)

Note the string constant must end with a Zero i.e. BYTE "HelloWorld",0

If you want to add a carriage return to it then

BYTE "HelloWorld",13,0

Cheers

Praxis

william chan said...

You already expert in Propeller, no need the PPDB

Need something to play with lah.

Cluso99

You can use

serial.str(string"Hello World", $0D))

or

serial.str(@StrHelloWorld)

(the @ is required to indicate it is a pointer to the memory)

Phil Pilgrim (PhiPi)

The string pseudofunction requires parens:

serial.str(string("Hello World", $0D))

Also (and please correct me if I'm wrong), unless you're using the same string from more than one place in your program, or need to modify the string during execution, there's probably no advantage to using the DAT form.

-Phil

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'Still some PropSTICK Kit bare PCBs left!

BradC

Phil Pilgrim (PhiPi) said...
The string pseudofunction requires parens:

serial.str(string("Hello World", $0D))

Also (and please correct me if I'm wrong), unless you're using the same string from more than one place in your program, or need to modify the string during execution, there's probably no advantage to using the DAT form.

-Phil

You are absolutely correct. For every STRING() the compiler places an independent copy in the Bytecode.
Using a string in DAT and referencing it multiple times is _far_ more efficient.

Remember kiddies .. strings from STRING() are all null terminated, so make sure to remember the ",0" in the DAT declaration or you might find your strings run on past what you are expecting.*!%@&#*($}}}}}}}}}}}}}}}}^Z^Z^Z^Z^Z^Z

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Pull my finger!

william chan

I did

serial.str(string("Hello World")

without the $0D at the back (is that a null?) and it still works! without any extra exclamations.

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www.fd.com.my
www.mercedes.com.my

Mike Green

The $0D is a carriage return. The "Hello World" will usually display as you expect, but the next item will directly follow the "d" rather than appear on the next line. You do need balanced parentheses ... one close parenthesis for each open parenthesis.

Cluso99

The $0D is a carriage return (newline). (see an ASCII code chart for the character set $00-$1F which are control characters)

BradC

william chan said...
I did

serial.str(string("Hello World")

without the $0D at the back (is that a null?) and it still works! without any extra exclamations.

The null is '0' and is inserted by the compiler when you use STRING(). You only need to add it manually when you
declare a string in the DAT section

DAT

mystring byte "This is my string",0

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Pull my finger!