Is const jchar * null terminated string in c++?

hi,
i read through the complete JNI documentation.
i searched all possible srcs to know "is const jchar * string returned by method GetStringChars(JString,NULL) to c++ declared in jni.h is NULL terminated or not ?" but i couldn't find it.
please help me.
because i am using this const jchar * string directly in my c++ code by just casting it to (const WCHAR *)
sometimes it is crashing the jvm for no reason sorry! i dont know the reason.

timberlake1865 wrote:
i searched all possible srcs to know "is const jchar * string returned by method GetStringChars(JString,NULL) to c++ declared in jni.h is NULL terminated or not ?" but i couldn't find it.No.
by just casting it to (const WCHAR *)That of course is unlikely to be correct regardless of whether it was null terminated or not.

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Quick question about null terminator string!

Hello,
I always feel that a char array should end with a "\0".
But just to clear up something here, if I do:
char *a[10];
and I fill out the array with 10 characters, then, should we *always* append the "\0" at the end of this array?
And if so, should it be appended at a[9] location or a[10] ??? It confuses me a little because since the array is supposed to take 10 characters, then does the compiler save an extra space at the 11th character location for the null terminator string?
OR
Is it up to us to make sure we fill the array with up to 9 characters making sure to save the 10th location in the array for the null terminator string?
So in a nutshell, once we finish up with a char array do we do this:
a[9] = '\0';
or this:
a[10] = '\0';
I excuse the simple question but this has been haunting me for a while, but thanks for all replies!!!
r

Ok, a few misconceptions here.
I always feel that a char array should end with a "\0".
This is not strictly true. This is only true of the data is to be treated as a string. Often you will use a char array to hold binary data. Normally such binary data will NOT end in a NUL character. In fact, most binary data may contain
NUL characters sprinkled throughout the data.
char *a[10];
This is NOT an array of ten characters. This is an array of ten pointers to characters (or character arrays). You probably intended
char a[10];
You then state
I fill out the array with 10 characters, then, should we *always* append the "\0" at the end of this array?
Again, this depends on whether you intend the data to be a string or binary data. I will assume you mean string from here on out. For a string, yes you should probably always append a '\0' Of course you don't actually have room for that NUL --
see the following answer. (Actually there are some string APIs that let you pass in a number of characters to process and those will work with no terminating NUL, but frankly you are playing with fire when you do that so I would recommend always putting
the trailing NUL in myself.)
And if so, should it be appended at a[9] location or a[10]
The declaration "char a[10]" causes the compiler to reserve *exactly* ten bytes of data for that array. If you write to location a[10], that is the
eleventh byte and will cause undefined behavior. At best you might not notice anything bad. At worst it could cause any sort of crazy data corruption. It could easily crash your program.
You would need to write the NUL character at a[9]. Note that writing NUL at a[9] will overwrite the last byte that you put into that array.
As a side note here: This is why you try to always use a proper string class like std::string when using C++ -- it takes care of all of that for you, including growing the string larger if you fill it up. Then you don't need to worry
about these pesky details that are easy to get wrong.

Quick question about null terminator string in arrays?

Hello,
If I do this:
char volatile xxo_[20];
memset(xxo_, ' ', 20);
xxo_[1] = '\0';
Am I not supposed to see the '0' symbolizing the null terminated string in 2nd array location like this:
xxo_[]= {' ','0',' ',' ',' ',' ',' ',' ',' ',' ' ,' ',' ', ' ',' ',' ',' ',' ',' ',' ',' ',}
Why am I seeing this?
xxo_[]= {' ',' ',' ',' ',' ',' ',' ',' ',' ',' ' ,' ',' ', ' ',' ',' ',' ',' ',' ',' ',' ',}
Thanks for all replies!

Standard debugging paranoia applies.
Are you running the code you think you are? Do you need to recompile / rebuild / check your .exe against your source? Do you just have a corrupt .pdb that needs to be rebuilt? Nuke your exe and pdbs and start again.
Try introducing a source code error or something that won't compile to verify that you are running the code you think you are compiling. And if that works, then alter the program to do something else that you are expecting to work. For example,
change the memset ' ' to write an 'x' or something and see if you can observe that in your debugger.
This is obviously not a standalone reproduction of the problem. Try to avoid introducing other aspects that might contribute to confusing the issue. Can you write a simple hello-world-sized program that does just this without all the rest of
your program?
char volatile to_[20];
memset( (void*)to_, ' ', 20 );
to_[0] = 0;
Note that without the (void*) this won't compile in Visual C++ because of the
volatile qualifier.
What does the disassembly say? Does the code that was generated logically do what the C code you wrote is intended to do? Can you generate an assembly listing and examine that for logical flaws?
Are you building with any kind of optimization settings? sometimes breakpoints aren't where you think they are in "release mode" or optimized builds because instructions can be reordered and entire blocks of statements may be altered in ways
that don't affect the final results, but make things a bit mysterious during debugging.
Can you try a different debugger such as windbg and see if you observe the same thing?

Missing terminating null in string argument

When the statement is executed "if ((strstr (refData, "end section") != test) || (strstr (refData, "end file") != test))", it displayed "Missing terminating null in string argument".The error is about refData,refData is a variable.
I don't know why this problem turned up,because it did not always appear except serval parameters.
Please tell you how to resolve this problem.
Thank you!

C assumes that a string is a character array with a terminating null character. This null character has ASCII value 0 and can be represented as just 0 or '\0'. This value is used to mark the end of meaningful data in the string. If this value is missing, many C string functions will keep processing data past the end of the meaningful data and often past the end of the character array itself until it happens to find a zero byte in memory, see here
So in order to resolve the problem make sure that your string ends with a null character.

What is the difference between string != null and null !=string ?

Hi,
what is the difference between string != null and null != string ?
which is the best option ?
Thanks
user8729783

Like you've presented it, nothing. There is no difference and neither is the "better option".

NULL TERMINATOR

제품 : PRECOMPILERS
작성날짜 : 1997-06-24
space 가 포함된 char column 을 varchar2 로 변환
=============================================
space 를 제거하기 위해 RTRIM function 을 이용한다.
1) data type 이 varchar2 인 dummy table 을 만든다.
2)insert into dummy select rtrim(char_col) from original_table
을 사용한다.

cvervais wrote:
The null byte at the end of the message is raising the score enough to just cross the spam threshold. Perhaps check with Sun to see if it's possible to disable sending a null at the end of the MILTER data?For inter-operability with sendmail this is something we should be removing. For some reason all other milter data sent by the sendmail client is null terminated except the BODY data so it likely we missed this when developing the libmilter plugin.
I've logged a new bug, feel free to escalate via Sun Support for a backport to MS6.3:
bug #6750733 - "Milter: Extraneous null terminating character at the end of BODY data"
Regards,
Shane.

Null/Empty Strings use in ESB Database Adapter

Hi
I'm trying to use a database adapter to execute an update on a table with a composite primary key; one of the primary key columns sometimes contains an empty string, however whenever I try to call the adapter, it always converts this to a null value. Is there an easy way to force the adapter to use an empty string instead of a null?
Thanks.

the idea here is to execute the dbms statement, or the setpolicycontext statement in a db session, and being able to execute the next sql statement in the same db session.
This is possible with consecutive database adapters sharing the same db session.
and two db adapters sharing the same db session is possible, if you make sure that the bpel is participating in the db transaction which can be made possible via xa db connections.
Hope this helps,
Write back in case you need more info.

Please tell basic difference between "" and null for String variable.

1.What is difference between String strRemitInfo = "" and String strRemitInfo = null?
2. Which one is good practice while coding ?

1.What is difference between String strRemitInfo = ""
and String strRemitInfo = null?Emptry string and nul reference
>
2. Which one is good practice while coding ?Depends on what you want to do.

Null query string in servlet filter with OC4J 10.1.3.1.0

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I got the same problem. I tried in others application servers alternatives and it works. By now i have to change links like this "http://localhost:8888/SIVIUQ/LoadIndex.portal?test=1" for forms using javaScript to send the parameters corresponding to the button pressed. To use buttons instead links is not the better solution due to usability. Any suggestion to solve this problem?
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Yo tengo el mismo problema. He intentado con otros servidores de aplicaciones y funciona. Por ahora tengo que cambiar links como "http://localhost:8888/SIVIUQ/LoadIndex.portal?test=1" por formularios, usando javaScript para enviar los parametros correspondientes al boton presionado. Usar botones en vez de links no es la mejor solucion debido a usabilidad. ¿Alguna sugerencia para resolver este problema?
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Mapping of line/port (Physical Channel constant) to pfi (Terminal Constant)

Hello all,
I am using "Dev1/port0/line4" (Physical channel constant) of my PXI-6602 as a digital input.
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Grüße
Phili

Having faced the same problem, I think I can say why there is no mapping.
Channels are for data aquistion, so actually a DAC, ADC, DO-Driver ...
Terminals are used for timing (trigger) and internally routed. So a diffrent concept, and a diffrent circuit.
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Sending a termination string [Ctrl-S] on socket

hi,
I'm trying to pass data to a server using socket. The server keeps on listening to a request until it receives the defined termination character/ command which is Ctrl-s .
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- Thanks
abhi

Find an ASCII table on the Internet.
Look up Ctrl/S.
Send that value as a byte.

How to distinguish NULL and Empty Strings

Hi,
Just to set the context right; I'm an experienced C programmer trying labview for the first time. As such I ran in to a problem being that Labview has no concept of NULL-pointers and more specifically appears to have no concept of the difference between a NULL-string and an empty-string
I'm trying to make a structure (bundle) of strings (in it's most basic form key-value pairs) which i'd like to (for instance) URI encode in order to send it to a web server. For those who are not familiar with URI encoding; there is a distinguished difference between setting a key to an empty string and setting a key with no value. In C I would use a pointer to an empty string vs a NULL string pointer to symbolize this.
In essence I need an elegant way to distinguish between a defined but empty string and an undefined string (hmmm this is actually describing the same problem but now in terms of perl).
Anybody have any pointers (pun not intended) for me ?

This is a bit depending on the interface you have with your encoder. The whole issue is that LV has no pointers at all (and you will like it, as you will never have any Null-Pointer exeptions and the like).
Assuming that you use a dll (so the Call Library node).
Use CString as input -> NULL-Terminated String.
Use I32 as input and pass 0 -> NULL string.
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www.aescusoft.de
My latest community nugget on producer/consumer design
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Match Pattern does not function properly when searching for a null character

I'm using Match Pattern to extract a null terminated string from a response I'm getting from a device on a serial port. The VI is attached and below is a screenshot of the block diagram.
It works just fine with index set to 0, 1, or 2. When index is 3, I get the output shown below.
Why is Match Pattern not finding the null character?
Thanks!
Solved!
Go to Solution.
Attachments:
Grab Nullterm String.vi ‏15 KB

I'm a dope, need to remove the wire from the Offset control to the Match Pattern control.
DUH!

Passing strings to a LAbVIEW application from Visual-C++ using ActiveX

Hello all,
I have built a LabVIEW application with ActiveX server enabled. I can
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But now I want to pass (SetControlValue) strings and read (GetControlValue) strings from controls.
After searching a whole day for examples or HowTos I found nothing. Can
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The problem you are running into is that a BSTR is not a normal string (%s in the printf), but a wide character string (i.e., two bytes per character) string with the size stored in it. If the string contains ASCII characters, such as Hello World, then the one of the bytes per character is 0 (for example, 'H' would be 0x48 0x0).
When printf sees this, it thinks that it is a normal, null terminated string of "H". That is what you are seeing. You might try the %S (capital S) since that tells it the string is a wide character string.
Also note that BSTR's are part of the COM (Automation) system and so are don't freed with a delete or free() statement. Instead you need to release the memory with a SysFreeString() call.
If you aren't very familiar with C/C++, then you've taken on an advanced topic on top of a complicated language. If you can, you might want to try using either VB6 or .NET (C# or VB.NET). Those languages handle all of this for you automatically and you don't have to worry about freeing the memory.
If not, the book I started with to learn COM programming was this one (http://www.amazon.com/gp/product/1572313498/104-3574382-6511132?v=glance&n=283155&n=507846&s=books&v...).
Brian Tyler
http://detritus.blogs.com/lycangeek

String data passed to DDC_SetDataValues

Using the DIAdem connectivity library, you can call DDC_SetDataValues to store data in a channel. If the channel contains string data, what is the format for the values parameter? My guess would be a sequence of back-to-back null-terminated strings but the API documentation does not say.
Solved!
Go to Solution.

I figured this out. When storing string data, DDC_SetDataValues takes a pointer to an array of pointers to C strings, like DDC_GetDataValues.
This is documented for DDC_GetDataValues. It should also be documented for DDC_SetDataValues.

Is const jchar * null terminated string in c++?

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