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Hello

I have the following "easy" problem. I have a string which contains
1000 chars.
Now my task is to cut the string at his 650 position. I tried strcpy,
to copy the first 650 chars into another string but I got a memory
access error. I have heard that i can use this function only to copy
500 chars is that true? What other options do i have?

Best Regards
Patrick

In article < .com>,
Patrick <> wrote:
>I have the following "easy" problem. I have a string which contains
>1000 chars.
>Now my task is to cut the string at his 650 position. I tried strcpy,
>to copy the first 650 chars into another string but I got a memory
>access error. I have heard that i can use this function only to copy
>500 chars is that true? What other options do i have?

No, that is NOT true. strcpy's lower limits are in the gigabyte range
when there are any limits at all. [After a few gigabytes, you
start overflowing 32 bit pointers...]

Note that if you only want to copy the leading part of a string,
strcpy is not the right function to use. I suggest you reexamine
the documentation for functions that have the letter 'n' in their
names.
--
This signature intentionally left... Oh, darn!

I tried it with strncpy but i get again a memory access violation....

Am Mon, 15 Aug 2005 23:56:01 -0700 schrieb Patrick:

> Hello
>
> I have the following "easy" problem. I have a string which contains
> 1000 chars.
> Now my task is to cut the string at his 650 position.
string[650] = '\0';

> I tried strcpy,
> to copy the first 650 chars into another string but I got a memory
> access error.
man strncpy
Does the second string have enough memory?

> I have heard that i can use this function only to copy
> 500 chars is that true?
The length of a character array is determined by NULL. The limitation is
the free heap space.

> What other options do i have?
Read a good C book.


Best Regards,
Stefan

Patrick wrote:
> Hello
>
> I have the following "easy" problem. I have a string which contains
> 1000 chars.
> Now my task is to cut the string at his 650 position. I tried strcpy,
> to copy the first 650 chars into another string but I got a memory
> access error. I have heard that i can use this function only to copy
> 500 chars is that true? What other options do i have?
>
> Best Regards
> Patrick

char *strncpy(char * restrict s1, const char * restrict s2, size_t n)
Make sure that you understand the function correctly.

Krishanu

Will you please write how your program exactly looks like?

Patrick wrote:
> I tried it with strncpy but i get again a memory access violation....

Patrick wrote:
> I tried it with strncpy but i get again a memory access violation....
1. Quote context.
2. Are you sure you are allocating memory before calling str*cpy()?
And, remember, you need to allocate strlen(whatever) + 1 chars, to make
room for the terminating null character. Also, post the offending code.

Patrick wrote:
> Hello
>
> I have the following "easy" problem. I have a string which contains
> 1000 chars.
> Now my task is to cut the string at his 650 position. I tried strcpy,
> to copy the first 650 chars into another string but I got a memory
> access error. I have heard that i can use this function only to copy
> 500 chars is that true? What other options do i have?
>
> Best Regards
> Patrickint

I think the following code solves ur problem...

main()
{
char st1[1000],st2[650];
int i;

for (i = 0; i < 1000; i++)
st1[i] = 'a';

st1[i] = '\0';

strncpy(st2,st1,sizeof(st2));
st2[650] = '\0';

for (i = 0; st2[i] != '\0'; i++)
printf("%d\t%c\n",i,st2[i]);

printf("%d",i);

}

Coder wrote:
> Patrick wrote:
>
>>Hello
>>
>>I have the following "easy" problem. I have a string which contains
>>1000 chars.
>>Now my task is to cut the string at his 650 position. I tried strcpy,
>>to copy the first 650 chars into another string but I got a memory
>>access error. I have heard that i can use this function only to copy
>>500 chars is that true? What other options do i have?
>>
>>Best Regards
>>Patrickint
>
>
> I think the following code solves ur problem...
>

When you answer, try to be sure that what you are proposing works ok...

> main()
> {

Shoyld always be

int main(void)
{

> char st1[1000],st2[650];
> int i;
>
> for (i = 0; i < 1000; i++)
> st1[i] = 'a';
>
> st1[i] = '\0';

You have already passed the limits of your st1... You try to access
st1[1000] which is wrong and produces an error in a well-written system..

>
> strncpy(st2,st1,sizeof(st2));
> st2[650] = '\0';

Same mistake here. Moreover, strncpy() does copy the ending '\0' so
there is no need for the erroneous st2[650] = '\0';
>
> for (i = 0; st2[i] != '\0'; i++)
> printf("%d\t%c\n",i,st2[i]);
>
> printf("%d",i);
>

And add a
return 0;

> }
>


--
one's freedom stops where other's begin

Giannis Papadopoulos
http://dop.users.uth.gr/
University of Thessaly
Computer & Communications Engineering dept.

Coder wrote:
> Patrick wrote:
> > Hello
> >
> > I have the following "easy" problem. I have a string which contains
> > 1000 chars.
> > Now my task is to cut the string at his 650 position. I tried strcpy,
> > to copy the first 650 chars into another string but I got a memory
> > access error. I have heard that i can use this function only to copy
> > 500 chars is that true? What other options do i have?
> >
> > Best Regards
> > Patrickint
>
> I think the following code solves ur problem...
>
No. It doesn't.

To start with, you need a few basic headers:

#include <stdio.h>
#include <string.h>

> main()

So, what did you say, your code compiled on?
Use

int main()
> {
> char st1[1000],st2[650];
> int i;
>
> for (i = 0; i < 1000; i++)
> st1[i] = 'a';
>
> st1[i] = '\0';

i is now thousand, and accessing out-of-bounds isn't correct.
I warned about *this* thing only in my previous post, please
take the time out to read the whole thread. Please!

>
> strncpy(st2,st1,sizeof(st2));
> st2[650] = '\0';
>
> for (i = 0; st2[i] != '\0'; i++)
> printf("%d\t%c\n",i,st2[i]);

Indentation is most welcome, btw.

> printf("%d",i);
>

Hm. No \n at end of printf(). You sure you know what you are
doing?

Also a little
return 0;
wouldn't hurt.
> }