Problem the Strings in C++

gjagadish · 10-15-2005, 01:49 AM

Hi guys,

i wrote one simple program in C++ as follows,

#include<iostream.h>
#include<string.h>
main()
{
char *temp="How are you";
char *ret="";
strcpy(ret,temp);
cout<<temp;
}

It is running in windows fine.
But with linux, it gives "Segmentation Fault (core dumped)" Error.
But it compiles with no error.

If i change the destination variable in strcpy to fixed array size like
char ret[100];

it works fine in linux.

why linux is not accepting the destination as pointer char.

thanx in advance
Jagadish

jlliagre · 10-15-2005, 02:05 AM

The question should be, "Why is Windows accepting running this buggy code ?"
No surprise so many viruses are happy in the Windows ecosystem !

gjagadish · 10-15-2005, 02:14 AM

Hi,

Can u explain me what is wrong with that code.

Can't we use the char pointer as destination in strcpy.

thanx for ur reply
Jagadish

spooon · 10-15-2005, 03:43 AM

The problem is that the character array at "ret" is not large enough (only 1 char) to hold the null-terminated string "How are you" (12 chars) and you're writing past the end of the array into other parts of memory.

jlliagre · 10-15-2005, 03:45 AM

You can use a char pointer as destination, but it need to point to some memory you are allowed to write to and with sufficient storage.
This pointer is initialized in your code to a one byte array that may or may not be writable, depending of the compiler implementation/options, the strcpy is also trashing some part of your windows stack as you are overwriting whatever is after this one byte array with the remaining of your source string.