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struct type ptr

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joker
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Re: struct type ptr
« Reply #12 on: Nov 19^th, 2015, 2:08pm »

Chill out, Richard and read ALL of my posts. embarassed

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Richard Russell
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Re: struct type ptr
« Reply #13 on: Nov 19^th, 2015, 2:39pm »

on Nov 19^th, 2015, 2:08pm, pnlawrence wrote:

I know why I didn't try CHAR[], here's what the LB help file lists as types

It is certainly extremely strange that CHAR isn't mentioned at all in the LB Help file (as far as I have been able to find), and stranger still that it wasn't added in the recently updated LB 4.5.0 docs. It isn't some minor 'feature' or subtlety that would benefit from being clarified, but an essential language element without which many Windows API functions couldn't readily be used.

I hope the explanation isn't that Carl knows it to be unreliable. There is one issue that I am aware of (fixed in LBB) which is that CHAR[1] is effectively unusable in LB 4.04 and 4.5.0. This code works in LBB but not in LB:

Code:

    struct test, c$ as char[1]
    test.c$.struct = "a"
    print test.c$.struct

The reason for the failure in LB is that strings stored in a CHAR member are assumed to be NUL-terminated, and if there's space for only a single character there is no room for the termination.

LBB treats this as a special case. If the member is declared as CHAR[2] or larger then a NUL-termination is included just the same as with LB, so CHAR[12] will hold at most an 11-character string. But with CHAR[1] no NUL-termination is added, ensuring that a single-byte structure member can be used successfully.

Richard.

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joker
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Re: struct type ptr
« Reply #14 on: Nov 19^th, 2015, 4:17pm »

Mr. Gundel needs to hire me to be his "bumbling around and finding problems" guru. cheesy

Along with describing my problematic experience with installing LB, this discovery of the missing "CHAR[i]" type makes two bumbles.

I'd have to charge way too much per bumble to make it a commercial endeavor, though. cheesy

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Richard Russell
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Re: struct type ptr
« Reply #15 on: Nov 19^th, 2015, 4:51pm »

on Nov 19^th, 2015, 4:17pm, pnlawrence wrote:

Mr. Gundel needs to hire me to be his "bumbling around and finding problems" guru. cheesy

Although you probably don't want a serious answer to a frivolous post, there's little evidence that Carl cares. angry

In 'updating' LB from 4.04 to 4.5.0 he has failed to address the majority of bugs recorded at the Liberty BASIC Bug Tracker Wiki. I would have expected him to go through that list and either fix every bug or explain why he is unable or unwilling to do so. I am prepared to accept that some bugs may be considered insufficiently important to warrant the time and effort it would take to fix them, and even that some are impractical to fix because of limitations in his tools, but we should be told that.

Instead, major bugs (like TIMER being unable to use a SUB handler) remain unfixed in LB 4.5.0 with no explanation.

Richard.

« Last Edit: Nov 19^th, 2015, 4:53pm by Richard Russell »

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joker
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Re: struct type ptr
« Reply #16 on: Nov 19^th, 2015, 5:19pm »

After trying to compile the previous code in LB, the compiler error message related that CHAR[12] is an illegal type.

Not a type and not even a reserved word.

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joker
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Re: struct type ptr
« Reply #17 on: Nov 19^th, 2015, 5:26pm »

I would like to do something like this:

Code:

function WriteINIStruct1(SectionName$,KeyName$,KeyChars$,inifile$)
    ' Returns true (1) if nothing wrong or false (0) if a problem
    'code by Richard Russell
    size = len(KeyChars$) * 2 + 1
    struct structName, keychars$ as CHAR[size]
    structName.keychars$.struct = KeyChars$
    size = len(structName.struct) 
    calldll #kernel32, "WritePrivateProfileStructA", _ 
    SectionName$ as ptr, _  ' Section name 
    KeyName$ as ptr, _    ' Key name 
    structName as struct, _   ' Structure 
    size as ulong, _      ' Size of structure 
    inifile$ as ptr, ret as long
    WriteINIStruct = ret
end function

However, LBB seems to choke on this with a "struct not defined error". Either I can't define the struct within the function or it doesn't like the variable within the CHAR[ statement. I can't tell which.

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Richard Russell
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Re: struct type ptr
« Reply #18 on: Nov 19^th, 2015, 5:42pm »

on Nov 19^th, 2015, 5:19pm, pnlawrence wrote:

After trying to compile the previous code in LB, the compiler error message related that CHAR[12] is an illegal type.

I don't get an error message from either LB 4.04 or LB 4.5.0 with the code I listed. Are you definitely using exactly the code I listed in my earlier post?

Quote:

I would like to do something like this:
Code:

struct structName, keychars$ as CHAR[size]

You can't. LB and LBB must know the size of the STRUCT at compile time, so you can't specify something like CHAR[size] because then the size is known only at run time. This is quite normal in other languages too.

You should specify whatever the maximum required size is, so if your string has a maximum length of 255 characters specify CHAR[256] (including the terminating NUL).

Richard.

« Last Edit: Nov 19^th, 2015, 5:53pm by Richard Russell »

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joker
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Re: struct type ptr
« Reply #19 on: Nov 19^th, 2015, 6:39pm »

I probably had the CHAR[size] code in the first trial. I know where to go now.

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joker
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Re: struct type ptr
« Reply #20 on: Nov 21^st, 2015, 12:43am »

I can make this code operate, but I can't make the "Get" work as a FUNCTION by returning the value. I had to pass a variable BYREF. It works, but wasn't my goal.

I speculate that since I am passing the STRUCT name that the FUNCTION is working on a copy of STRUCT. Interesting.

Any ideas on returning the STRUCT value with a FUNCTION?

Also, I found out that CHAR[10] really only stores a string of 9 characters. I guess the rest is overhead? I don't understand why specifying [10] in the code doesn't save 10.

OUTPUT LOOKS LIKE THE FOLLOWING:

Code:

[settings]
config=30313233343536373839000D

Code:

if right$(DefaultDir$,1)<>"\" then
    DefaultDir$=DefaultDir$+"\"
end if
inifile$ = DefaultDir$ + "JunkINIstruct.ini"

print inifile$

struct structName, keychars$ as CHAR[11] ' if CHAR[10] you can only write 9 characters

ret = WriteINIStruct1("settings","config","0123456789",structName,inifile$)
print "ret from write: ";ret

'structName.keychars$.struct = ""
'print "test struct clear: "+structName.keychars$.struct

ret = GetINIStruct1("settings","config",GetKeyChars$,structName,inifile$)
print "ret from get: ";ret
print "Got this: ->"+GetKeyChars$+"<- (from GetINIStruct1)"

end

function WriteINIStruct1(SectionName$,KeyName$,KeyChars$,structName,inifile$)
    ' Returns true (1) if nothing wrong or false (0) if a problem
    'code by Richard Russell
    structName.keychars$.struct = KeyChars$
    size = len(structName.struct) 
    calldll #kernel32, "WritePrivateProfileStructA", _ 
    SectionName$ as ptr, _  ' Section name 
    KeyName$ as ptr, _    ' Key name 
    structName as struct, _   ' Structure 
    size as ulong, _      ' Size of structure 
    inifile$ as ptr, ret as long
    WriteINIStruct1 = ret
end function

function GetINIStruct1(SectionName$,KeyName$,byref GetKeyChars$,structName,inifile$)
    ' Returns true (1) if nothing wrong or false (0) if a problem
    'code by Richard Russell
    size = len(structName.struct) 
    calldll #kernel32, "GetPrivateProfileStructA", _ 
    SectionName$ as ptr, _  ' Section name 
    KeyName$ as ptr, _    ' Key name 
    structName as struct, _   ' Structure 
    size as ulong, _      ' Size of structure 
    inifile$ as ptr, ret as long
    GetKeyChars$ = structName.keychars$.struct
    'GetINIStruct1 = structName.keychars$.struct ' this won't work. "Type mismatch" error.
    GetINIStruct1 = ret
end function

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Richard Russell
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Re: struct type ptr
« Reply #21 on: Nov 21^st, 2015, 03:35am »

on Nov 21^st, 2015, 12:43am, pnlawrence wrote:

I can't make the "Get" work as a FUNCTION by returning the value.

I wonder if the problem is as simple as forgetting that a function which returns a string must itself have a name ending in a dollar. So for example the function might be called GetINIStruct1$().

Quote:

I speculate that since I am passing the STRUCT name that the FUNCTION is working on a copy of STRUCT.

STRUCTs in Liberty BASIC are always global. You cannot pass a struct as a parameter to a SUB or FUNCTION. Is that what you were hoping to be able to do?

Quote:

I don't understand why specifying [10] in the code doesn't save 10.

You berated me the other day for not reading all of your messages, now you're not reading all of mine! I wrote: "strings stored in a CHAR member are assumed to be NUL-terminated ... so CHAR[12] will hold at most an 11-character string."

Richard.

« Last Edit: Nov 21^st, 2015, 04:07am by Richard Russell »

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tsh73
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Re: struct type ptr
« Reply #22 on: Nov 21^st, 2015, 03:57am »

Quote:

Also, I found out that CHAR[10] really only stores a string of 9 characters. I guess the rest is overhead? I don't understand why specifying [10] in the code doesn't save 10.

ABS of API#5 says
Quote:

The GetWindowTextA function also requires an argument that specifies the length of the string buffer. We can get the length with the LEN() function, like this:

length=len(Caption$) + 1

We add 1 to the length argument because Liberty BASIC adds a null termination character to strings passed into API calls.

Also, wikipedia::Null-terminated string

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joker
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Re: struct type ptr
« Reply #23 on: Nov 21^st, 2015, 08:51am »

Ok, ok. At least I only make simple mistakes. rolleyes

The old "$" specification problem. The error message was telling me, but I wasn't listening.

I thought I tried struct as GLOBAL but ... Oh well, I have an eye doctor appointment coming up. embarassed

The last character at the end of the OUTPUT (in Notepad) looks like a "D" I haven't looked at it with anything else. I was thinking how did a CR get there?

PS. Richard, I don't "berate". I just gently "chide." cheesy

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joker
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Re: struct type ptr
« Reply #24 on: Nov 21^st, 2015, 09:15am »

I remember now.

tsh73 posted (on that "other" forum) that the API puts a CHECKSUM on the end.

The last 2 bytes are the checksum. (The least significant byte of the sum of all the ASCII values.)

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joker
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Re: struct type ptr
« Reply #25 on: Nov 21^st, 2015, 09:39am »

I found out that CHAR[32766] is the largest that works with the API (or is it a limit of CHAR[]?) That's plenty of room for INI stuff. I suppose there's a problem with running out of something while the program is running if the STRUCT gets too large.

Its a little clunky, because the name of the STRUCT is coded into the FUNCTION, but I envision several specific FUNCTIONs with several specific STRUCTs writing to the same INI file.

Maybe obfuscation isn't so clunky after all? :D

Code:

if right$(DefaultDir$,1)<>"\" then
    DefaultDir$=DefaultDir$+"\"
end if
inifile$ = DefaultDir$ + "JunkINIstruct.ini"

print inifile$

struct structName, keychars$ as CHAR[32766] ' fails when CHAR[32766] is exceeded

ret = WriteINIStruct1("settings","config","0123456789:",inifile$)
print "ret from write: ";ret

print "Got this: ->"+GetINIStruct1$("settings","config",inifile$)+"<- (from GetINIStruct1$)"

end

function WriteINIStruct1(SectionName$,KeyName$,KeyChars$,inifile$)
    ' Returns true (1) if nothing wrong or false (0) if a problem
    'code by Richard Russell
    structName.keychars$.struct = KeyChars$
    size = len(structName.struct) 
    calldll #kernel32, "WritePrivateProfileStructA", _ 
    SectionName$ as ptr, _  ' Section name 
    KeyName$ as ptr, _    ' Key name 
    structName as struct, _   ' Structure 
    size as ulong, _      ' Size of structure 
    inifile$ as ptr, ret as long
    WriteINIStruct1 = ret
end function

function GetINIStruct1$(SectionName$,KeyName$,inifile$)
    ' Returns string value if nothing wrong or NULL if a problem
    'code by Richard Russell
    size = len(structName.struct) 
    calldll #kernel32, "GetPrivateProfileStructA", _ 
    SectionName$ as ptr, _  ' Section name 
    KeyName$ as ptr, _    ' Key name 
    structName as struct, _   ' Structure 
    size as ulong, _      ' Size of structure 
    inifile$ as ptr, ret as long
    if ret = 0 then GetINIStruct1$ = "" : exit function
    GetINIStruct1$ = structName.keychars$.struct
end function

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Richard Russell
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Re: struct type ptr
« Reply #26 on: Nov 21^st, 2015, 10:00am »

on Nov 21^st, 2015, 09:39am, pnlawrence wrote:

I found out that CHAR[32766] is the largest that works with the API (or is it a limit of CHAR[]?)

I'm really not sure what you are trying to achieve. If you are storing a single string, especially if it is quite a long string, using a STRUCT isn't a particularly appropriate method. For example it stores more than twice as much data in the INI file as it needs to (each character of the string gets expanded to two hex characters).

If your objective is to obfuscate the string, storing it as hex will defeat only the most simplistic attempts at reading it. Many people will immediately recognise hex text, and either be able to read it 'by inspection' or simply copy-and-paste it into their favourite hex editor.

A trivial encryption technique, like XOR-ing each character of the string with a pseudo-random key, would be much more effective and not waste space in the file. STRUCTs wouldn't be involved at all.

Richard.

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