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1.38 BUG: errors at string and char[] operations

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1.38 BUG: errors at string and char[] operations

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Ford Prefect

Senior Roboticist

Joined: Sat Mar 01, 2008 12:52 pm
Posts: 936
Location: a small planet in the vicinity of Beteigeuze

hi,
@tyro: what will us tell your codes?
Is RobotC working faulty or is there just no ANSI-compatibility?

@developers: PLEASE make RobotC work like REAL C !!
This is actually what you have been advertising!!

_________________
Ford Prefect

Never purchase release 1.x ! (ancient programmer's wisdom)
"Don't argue with idiots. They'll drag you down to their level and then beat you with experience."

Tue Jul 01, 2008 11:03 am

tyro

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Joined: Wed Jun 25, 2008 9:38 pm
Posts: 6

Wonderful. Has anyone tried out StringDelete()? As far as I can see that procedure does nothing!!
(Which is incredibly annoying, since the documentation tells me something else.)
I also wonder why these things are procedures at all. They don't implement pointers: Fine. But then they should do some magic and make them functions, otherwise they don't simplify anything.

Anyway, please developers, implement StringDelete(), as well as some procedure to get a string out of chars!

Tue Jul 01, 2008 2:38 pm

tyro

Rookie

Joined: Wed Jun 25, 2008 9:38 pm
Posts: 6

Finally, I found at least a small part of the problem....

if you tell your program you would like to have to arrays of strings,


	Code: string a[16], b[16];

and then initialize the secound array before the first one,


	Code: b[0] = "Good stuff breaks" a[0] = "Something else"

you will break your program.
I'm completely fed up with this stuff.

Wed Jul 02, 2008 7:33 am

Ford Prefect

Senior Roboticist

Joined: Sat Mar 01, 2008 12:52 pm
Posts: 936
Location: a small planet in the vicinity of Beteigeuze


	tyro wrote: Wonderful. Has anyone tried out StringDelete()? As far as I can see that procedure does nothing!

what is this function or proc supposed to do anyway?
in what case is a string deletion needed for?
in C or C++ I don't know such a function name.
if you want a string to be "deleted" it will be the easiest way to assign it to a NullString :
string s;
char cstr[20];
s="";
cstr="";

ceterum censeo: RobotC has to become REAL C !

_________________
Ford Prefect

Never purchase release 1.x ! (ancient programmer's wisdom)
"Don't argue with idiots. They'll drag you down to their level and then beat you with experience."

Last edited by Ford Prefect on Tue Jul 08, 2008 5:09 am, edited 4 times in total.

Thu Jul 03, 2008 9:46 am

tyro

Rookie

Joined: Wed Jun 25, 2008 9:38 pm
Posts: 6

Very good question. I wanted to use this function as a replacement for the missing "substring" functionality (I still haven't found any stable way of working with substrings, and the missing pointers prevent me from finding an acceptable workaraound :cry:

).

But now that I think about it: such a "delete" procedure is either predestined to mess up the memory, or to be slow and useless.

Sat Jul 05, 2008 6:12 am

Ford Prefect

Senior Roboticist

Joined: Sat Mar 01, 2008 12:52 pm
Posts: 936
Location: a small planet in the vicinity of Beteigeuze

aaah - now that I read your post again, I guess I know what it's supposed to do:
stringdelete(mystring,2,5)
may delete in mystring 5 characters starting with position 2 (=3rd char) - or other way around... :roll:

but what should mystring be ? char array or C++ string ?

and in ANSI C


	Code: char chrstr[20]="abcdefg"

is a valid assignment! why not in RobotC?? :evil:

@dick swan, @tfriez,
could you plz give a statement to all of these string processing problems?
thx in advance!

_________________
Ford Prefect

Never purchase release 1.x ! (ancient programmer's wisdom)
"Don't argue with idiots. They'll drag you down to their level and then beat you with experience."

Tue Jul 08, 2008 2:41 am

Ford Prefect

Senior Roboticist

Joined: Sat Mar 01, 2008 12:52 pm
Posts: 936
Location: a small planet in the vicinity of Beteigeuze

I tried the code again with the 1.38:
this original C code from a textbook does not work correctly (actually it doesn't work at all):


	Code: #define printf nxtDisplayTextLine char name1[8], name2[8], temp[20]; task main(){ // here the original C code starts strcpy(name1,"Athene"); strcpy(name2,"Zeus"); if (strcmp(name1,name2)>0) { strcpy(temp,name1);} else strcpy(temp, name2); printf(1, "%s","bigger: "); printf(2, "%s", temp); strcpy(temp,""); strcat(temp, name1); strcat(temp, " & "); strcat(temp, name2); printf(3, "%s", "both: "); printf(4, "%s", temp); // here the original C code ends while(true){}; }

the display shows just:


	Quote: bigger: 0 both:

instead of


	Quote: bigger: Zeus both: Athene & Zeus

_________________
Ford Prefect

Never purchase release 1.x ! (ancient programmer's wisdom)
"Don't argue with idiots. They'll drag you down to their level and then beat you with experience."

Fri Jul 25, 2008 4:22 pm

Ford Prefect

Senior Roboticist

Joined: Sat Mar 01, 2008 12:52 pm
Posts: 936
Location: a small planet in the vicinity of Beteigeuze

Re: 1.38 BUG: errors at string and char[] operations

Here's a post from Dick Swan (out of Bug Tracker);
My idea: maybe you can exchange


	Code: DisplayTextLine // RobotC dialect


	Code: printf // ANSI C syntax

in the following definition and add it to the file RobotCIntrinsics.c

Then you will have both, the RobotC/C++ string print command, and the ANSI C printf command for charstr.


	Dick Swan wrote: I've tested the code. The string functions -- strcpy, strcmp, strcat -- behave as exepected. The anomoly is in the print to LCD functions which does not behave as you expected. The difficulty is that ROBOTC does not support VA_ARG style variable lists of procedure parameters. And C is a little inconsistent on how these are supported. 1. For short, int, long and float parameter types, C stores the value of the parameter on the parameter "stack". 2. For char parameter types, C stores a pointer to the parameter on the stack. Most programmers will not use arrays of chars and instead will use ROBOTC's built-in (and memory leak, and bad pointer safe) "string" variable. If you want to exact C-style formating, then change the definition of the "NxtDisplayTextLine" built-in function in the file RobotCIntrinsics.c. Change the existing definition to the attached. One side effect of this change is that "%d" formating will not work with "byte" or "char" variables -- just like ANSI C. You have to cast to a short or int first. This is one of the reasons that this will not be a universal change in ROBOTC. Here's the revised definitions. #define DisplayTextLine(fmtType, type1, ref1, type2, ref2, default2)\ intrinsic void nxtDisplayTextLine(const int nLineNumber, const string &sFormatString, const type1 &parm1, const type2 &parm2 default2)\ asm(opcdNxtLCDDisplay, byte(nxtDsplyDrawTextLineVarVarFmtSpec), variable(nLineNumber),\ ref1(parm1), ref2(parm2),\ byte(fmtType), variableRefString(sFormatString)) DisplayTextLine(StringString,byte, variableRefByte, byte, variableRefByte, ); DisplayTextLine(StringShort, byte, variableRefByte, short, variableRefWord, ); DisplayTextLine(StringLong, byte, variableRefByte, long, variableRefLong, ); DisplayTextLine(StringFloat, byte, variableRefByte, float, variableRefFloat, ); DisplayTextLine(StringString,byte, variableRefByte, string, variableRefString, =""); DisplayTextLine(ShortString, short, variableRefWord, byte, variableRefByte, ); DisplayTextLine(ShortShort, short, variableRefWord, short, variableRefWord, ); DisplayTextLine(ShortLong, short, variableRefWord, long, variableRefLong, ); DisplayTextLine(ShortFloat, short, variableRefWord, float, variableRefFloat, ); DisplayTextLine(ShortString, short, variableRefWord, string, variableRefString, =""); DisplayTextLine(LongString, long, variableRefLong, byte, variableRefByte, ); DisplayTextLine(LongShort, long, variableRefLong, short, variableRefWord, ); DisplayTextLine(LongLong, long, variableRefLong, long, variableRefLong, ); DisplayTextLine(LongFloat, long, variableRefLong, float, variableRefFloat, ); DisplayTextLine(LongString, long, variableRefLong, string, variableRefString, =""); DisplayTextLine(FloatString, float, variableRefFloat, byte, variableRefByte, ); DisplayTextLine(FloatShort, float, variableRefFloat, short, variableRefWord, ); DisplayTextLine(FloatLong, float, variableRefFloat, long, variableRefLong, ); DisplayTextLine(FloatFloat, float, variableRefFloat, float, variableRefFloat, ); DisplayTextLine(FloatString, float, variableRefFloat, string, variableRefString, =""); DisplayTextLine(StringString,string, variableRefString, byte, variableRefByte, ); DisplayTextLine(StringShort, string, variableRefString, short, variableRefWord, ); DisplayTextLine(StringLong, string, variableRefString, long, variableRefLong, ); DisplayTextLine(StringFloat, string, variableRefString, float, variableRefFloat, ); DisplayTextLine(StringString,string, variableRefString, string, variableRefString, =""); #undef DisplayTextLine If you want to obtain C-style form

_________________
Ford Prefect

Never purchase release 1.x ! (ancient programmer's wisdom)
"Don't argue with idiots. They'll drag you down to their level and then beat you with experience."

Wed Aug 20, 2008 12:32 pm

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