Program Crash

[Kuku]

My Program is crashing at
strupr(e2.n);


int main()
{
struct emp
{
char *n;
int age;
};

struct emp e1={"Dravid",50};
struct emp e2;
e2=e1;
strupr(e2.n);
printf("\ne1.n=%s\n",e1.n);
return 0;
}

[Chris McDonald]

"Kuku" <me******@yahoo.com> writes:

My Program is crashing at
strupr(e2.n);

Your question is off topic in comp.lang.c.
The Standard C language does not define what a crashing program is.

--
Chris.

[Serge Paccalin]

Le mercredi 3 août 2005 à 11:30, Kuku a écrit dans comp.lang.c*:

My Program is crashing at
strupr(e2.n);
I guess you want ask us why?
int main()
{
struct emp
{
char *n;
int age;
};

struct emp e1={"Dravid",50};
The constant litteral "Dravid" is stored somewhere in a place of memory
you're not supposed to modify, and e1.n now points to that memory.
struct emp e2;
e2=e1;
Now e2.n points to the same memory as e1.n
strupr(e2.n);

Here, you try to write in that memory. Since you're not supposed to
modify it, anything can happen. That is undefined behavior.

--
___________ 03/08/2005 12:09:13
_/ _ \_`_`_`_) Serge PACCALIN -- sp ad mailclub.net
\ \_L_) Il faut donc que les hommes commencent
-'(__) par n'être pas fanatiques pour mériter
_/___(_) la tolérance. -- Voltaire, 1763

[Default User]

Chris McDonald wrote:

Your question is off topic in comp.lang.c.
The Standard C language does not define what a crashing program is.

Don't be an idiot.


Brian

[Emmanuel Delahaye]

Kuku wrote on 03/08/05 :

My Program is crashing at
strupr(e2.n);

int main()
{
struct emp
{
char *n;
int age;
};

struct emp e1={"Dravid",50};
struct emp e2;
e2=e1;
strupr(e2.n);
printf("\ne1.n=%s\n",e1.n);
return 0;
}

A string literal is not mutable. The copy of structures creates a new
pointer to the same not mutable string.

You want an array of char.

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

struct emp
{
char n[32];
int age;
};

int main ()
{

struct emp e1 =
{
.n = "David",
.age = 50,
};
struct emp e2 = e1;

strupr (e2.n);

printf ("e1.n=%s\n", e1.n);
printf ("e2.n=%s\n", e2.n);

return 0;
}

--
Emmanuel
The C-FAQ: http://www.eskimo.com/~scs/C-faq/faq.html
The C-library: http://www.dinkumware.com/refxc.html

I once asked an expert COBOL programmer, how to
declare local variables in COBOL, the reply was:
"what is a local variable?"

[Keith Thompson]

Serge Paccalin <[e-mail]> writes:

Le mercredi 3 août 2005 à 11:30, Kuku a écrit dans comp.lang.c*:

[...]

strupr(e2.n);

Here, you try to write in that memory. Since you're not supposed to
modify it, anything can happen. That is undefined behavior.

Assuming that strupr modifies the string to which e2.n points. That
seems likely, but there is no strupr() function in the standard.

Also, the original program is missing a #include directive for
<stdio.h> (it calls printf) and for whatever header declares strupr().

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.