Hello!
I need copy from structure "A" to "B" that contains "strings" in a one line code.
Me problem like this :
typedef struct tHeader{
char field1[4];
char field2[3];
char field3[2];
char field4[1];
};
struct tHeader Header,*pHeader;
char buffer[100];
pHeader=&Header;
strcpy(buffer,"ABCDEFGHIJKLMNOPQRSTUVWXYZ");
memcpy(pHeader,&buffer,sizeof (struct tHeader));
printf("field1 : %s : ",pHeader->field1);
printf("field2 : %s : ",pHeader->field2);
printf("field3 : %s : ",pHeader->field3);
printf("field4 : %s : ",pHeader->field4);
What i need ?
pHeader->field1 ==>"ABCD"
pHeader->field2 ==>"ABC"
pHeader->field3 ==>"AB"
pHeader->field4 ==>"A"
Someone helpme ?
Cheers! 3 2954
In article <dd**************************@posting.google.com >,
Leo Nunez <le*******@gmail.com> wrote:
:I need copy from structure "A" to "B" that contains "strings" in a one line code.
In the code you show, you are not copying structure to structure:
you are copying from a character array to a structure.
:typedef struct tHeader{
: char field1[4];
: char field2[3];
: char field3[2];
: char field4[1];
:};
:strcpy(buffer,"ABCDEFGHIJKLMNOPQRSTUVWXYZ");
:memcpy(pHeader,&buffer,sizeof (struct tHeader));
What about internal padding and alignments?
:printf("field1 : %s : ",pHeader->field1);
:pHeader->field1 ==>"ABCD"
You don't null terminate your strings, so the output could
run on indefinitely.
--
100% of all human deaths occur within 100 miles of Earth.
Leo Nunez wrote: Hello!
I need copy from structure "A" to "B" that contains "strings" in a one line code.
Assuming A and B are the same type of structure -- that
is, that they are both `struct foo' -- this is simple: B = A
will do it.
Me problem like this :
.... and here's where my confusion begins, because the
illustration doesn't resemble the problem statement.
typedef struct tHeader{ char field1[4]; char field2[3]; char field3[2]; char field4[1]; };
Fine; here's the structure type A and B will have, the
`struct foo' mentioned above.
struct tHeader Header,*pHeader;
All right, we have an instance of the structure, and
it's called Header. We don't know yet whether this is the
A or the B, but it'll be one or the other. We also have
a pointer that can refer to structures of this type, which
isn't something that was present in the problem statement --
but maybe things will become clearer as I read further.
char buffer[100];
An array of characters? What has that to do with the
price of eggs? You were asking about two structures; what
is this array for?
pHeader=&Header;
All right, the pointer now refers to the structure.
We still don't know whether it's the A or the B structure
(or why we're bothering with a pointer at all), but it
makes sense.
strcpy(buffer,"ABCDEFGHIJKLMNOPQRSTUVWXYZ");
Filling the useless array with some data that doesn't
appear relevant. Harmless, but it's still not clear why
the array is here.
memcpy(pHeader,&buffer,sizeof (struct tHeader));
Probably valid, but dubious in the extreme. It overlays
the structure instance with as many characters as will fit.
The first four characters go into the field1 element, and
some of the subsequent characters (you don't know exactly
which) go into the other elements. It is possible, although
unlikely, that sizeof(struct tHeader) is greater than the
size of buffer, in which case memcpy() will try to read beyond
the bounds of the array with unpredictable consequences.
Note that the elements of the structure will not be valid
C strings, since they lack '\0' terminators. Note also that
`&buffer' should probably be just `buffer'.
I do not understand what you are trying to accomplish
with this very strange operation.
printf("field1 : %s : ",pHeader->field1); printf("field2 : %s : ",pHeader->field2); printf("field3 : %s : ",pHeader->field3); printf("field4 : %s : ",pHeader->field4);
Since the fields are not valid C strings, all four of
these printf() calls produce undefined behavior.
What i need ?
Beyond my understanding, I'm afraid. What you want?
pHeader->field1 ==>"ABCD" pHeader->field2 ==>"ABC" pHeader->field3 ==>"AB" pHeader->field4 ==>"A"
Is this the output you're trying to produce? I don't
understand the connection between this output and the data
that are actually deposited into the structure elements.
We know that field1 will contain the four characters A B C D
(and no terminating '\0' because there's no room for it), but
we don't know what the remaining fields will contain. We know
they will *not* contain any of A B C D, though, since those
characters landed in field1 and don't occur again in buffer.
Why do you expect one A to appear four times?
Someone helpme ?
You'll need to explain your problem more clearly. What
you asked was simple enough, but your illustration makes no
sense at all. Not to me, anyhow.
Cheers!
Very well: "Hurrah!"
-- Er*********@sun.com
Leo Nunez wrote: Hello!
I need copy from structure "A" to "B" that contains "strings" in a one line code.
Me problem like this :
typedef struct tHeader{ char field1[4]; char field2[3]; char field3[2]; char field4[1]; };
struct tHeader Header,*pHeader;
char buffer[100];
pHeader=&Header;
strcpy(buffer,"ABCDEFGHIJKLMNOPQRSTUVWXYZ");
memcpy(pHeader,&buffer,sizeof (struct tHeader));
printf("field1 : %s : ",pHeader->field1); printf("field2 : %s : ",pHeader->field2); printf("field3 : %s : ",pHeader->field3); printf("field4 : %s : ",pHeader->field4);
What i need ?
pHeader->field1 ==>"ABCD" pHeader->field2 ==>"ABC" pHeader->field3 ==>"AB" pHeader->field4 ==>"A"
Someone helpme ?
Cheers!
I would think you would need a union to do that not a struct.
your printfs will not work since you strings have no nulls.
try printf("field1 : %4s : ",pHeader->field1); This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
by: Nick Jacobson |
last post by:
This question is with regard to the * operator as used for sequence
concatenation.
There's the well-known gotcha:
a = ]
b = a*3
b = 4
print b
|
by: Shagy |
last post by:
Greetings,
I've been trying to find an equivant c funtion to the c++ copy function.
Description:
copy(char *cstring, size_t count, size_t offset);
Copies "count" characters from a C-style...
|
by: Alfonso Morra |
last post by:
Hi,
I have the ff data types :
typedef enum {
VAL_LONG ,
VAL_DOUBLE ,
VAL_STRING ,
VAL_DATASET
}ValueTypeEnum ;
|
by: Eric Sabine |
last post by:
During a process in an app, I have a string created in code that I want
automatically saved in the user's cache so he can move to another program
and do a CTRL-V (or paste). This is easy I'm sure,...
|
by: rsine |
last post by:
I have developed a program that sends a command through the serial port
to our business system and then reads from the buffer looking for a
number. Everything worked great on my WinXP system, but...
|
by: Fei Liu |
last post by:
In Accellerated C++, the author recommends that in a header file one should
not declare
using std::string, using std::vector etc instead one should directly specify
the namespace specifier in...
|
by: tommak |
last post by:
It's a dream of human beings to build machines that can think and
behave like human beings. The most important part of of such a
machine is an artificial mind that can emulate the cognitive...
|
by: Özden Irmak |
last post by:
Hello,
Does anybody know a way to get the local equvalents of strings used by
explorer such as "Cut","Copy","Paste" ?
Thanks in advance...
Regards,
Özden Irmak
|
by: Jess |
last post by:
Hello,
The C++ reference says the return result of "copy" is an output
iterator. I'm wondering how I can assign the returned iterator to
some other iterator. I tried
int main(){
string...
|
by: ryjfgjl |
last post by:
If we have dozens or hundreds of excel to import into the database, if we use the excel import function provided by database editors such as navicat, it will be extremely tedious and time-consuming...
|
by: ryjfgjl |
last post by:
In our work, we often receive Excel tables with data in the same format. If we want to analyze these data, it can be difficult to analyze them because the data is spread across multiple Excel files...
|
by: BarryA |
last post by:
What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...
|
by: Sonnysonu |
last post by:
This is the data of csv file
1 2 3
1 2 3
1 2 3
1 2 3
2 3
2 3
3
the lengths should be different i have to store the data by column-wise with in the specific length.
suppose the i have to...
|
by: Hystou |
last post by:
There are some requirements for setting up RAID:
1. The motherboard and BIOS support RAID configuration.
2. The motherboard has 2 or more available SATA protocol SSD/HDD slots (including MSATA, M.2...
|
by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However,...
|
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers,...
|
by: jinu1996 |
last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven...
|
by: Hystou |
last post by:
Overview:
Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows...
| |