Newie question

[gabitoju]

I have this pice of code (I know, I should use c++ string instead of c
string):

char *p = new char[4];
strcpy(p, "Hola");
delete [] p;

With gcc I compile it and run it with no errors, but with MS Visual C++
6.0 I get an error that says:
"DAMAGE: after Normal block(#238) at [an address].

Someone can tell me wath´s wrong?

[Phlip]

gabitoju wrote:

char *p = new char[4];
strcpy(p, "Hola");

"Hola" is really "Hola\0", and strcpy() finds the end of the string by the
\0. (Not by the 4 on the previous line!)

However, p only points to 4 valid characters, so strcpy() writes the \0 off
the end of the array at p. This corrupts the heap, and VC++ in Debug mode
catches that, where gcc doesn't catch it.

Tip: Use std::string. ;-)

--
Phlip
http://www.greencheese.us/ZeekLand <-- NOT a blog!!!

[gabitoju]

It works!!!

Thak you

I´m using std:string for almost all string, but I use char* new[] to
use C strtok().

Phlip ha escrito:

gabitoju wrote:

char *p = new char[4];
strcpy(p, "Hola");

"Hola" is really "Hola\0", and strcpy() finds the end of the string by the
\0. (Not by the 4 on the previous line!)

However, p only points to 4 valid characters, so strcpy() writes the \0 off
the end of the array at p. This corrupts the heap, and VC++ in Debug mode
catches that, where gcc doesn't catch it.

Tip: Use std::string. ;-)

--
Phlip
http://www.greencheese.us/ZeekLand <-- NOT a blog!!!

[Thomas Matthews]

ga******@gmail.com wrote:

It works!!!

Thak you

I´m using std:string for almost all string, but I use char* new[] to
use C strtok().

Take a look at the "find" methods for string. They are very
valuable and do not modify the string.

--
Thomas Matthews

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[Phlip]

gabitoju wrote:

Thak you

Please don't top-post.

I´m using std:string for almost all string, but I use char* new[] to
use C strtok().

Like someone said, use find().

Then Google for strtok, and you'll find a gadzillion reasons not to use it.
Some even apply to newbies!

--
Phlip
http://www.greencheese.us/ZeekLand <-- NOT a blog!!!

[Victor Bazarov]

ga******@gmail.com wrote:

I have this pice of code (I know, I should use c++ string instead of c
string):

char *p = new char[4];
strcpy(p, "Hola");
delete [] p;

With gcc I compile it and run it with no errors, but with MS Visual
C++
6.0 I get an error that says:
"DAMAGE: after Normal block(#238) at [an address].

Someone can tell me wath´s wrong?

You allocate one char less than you copy. "Hola" has 5 chars in it.
You have to count the terminating '\0'.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Thomas Matthews]

ga******@gmail.com wrote:

I have this pice of code (I know, I should use c++ string instead of c
string):

char *p = new char[4];
strcpy(p, "Hola");
delete [] p;

With gcc I compile it and run it with no errors, but with MS Visual C++
6.0 I get an error that says:
"DAMAGE: after Normal block(#238) at [an address].

Someone can tell me wath´s wrong?

Try this safer code:
const char hola[] = "Hola";
char * p;
p = new char [sizeof(hola)];
strcpy(p, hola);
cout << p;
delete [] p;
--
Thomas Matthews

C++ newsgroup welcome message:
http://www.slack.net/~shiva/welcome.txt
C++ Faq: http://www.parashift.com/c++-faq-lite
C Faq: http://www.eskimo.com/~scs/c-faq/top.html
alt.comp.lang.learn.c-c++ faq:
http://www.comeaucomputing.com/learn/faq/
Other sites:
http://www.josuttis.com -- C++ STL Library book
http://www.sgi.com/tech/stl -- Standard Template Library