Char Pointer error!

First of all, i know this code is wrong and i know how to fix it hopefully! However, i do not know why the green point is wrong! I mean that i try to have a char pointer named "name" but...what is going wrong with this?
thanks in advance...

Code:

---

#include <iostream>

using namespace std;

int main(void){
    char *name;
        cout << "name: ";
        cin >> name;
        cout << "your name is: " << &name << "\n";
return 0;
}

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One problem is that you only have a pointer to char; you don't have any space to actually store a name. Another problem is that if you want to print the name, you should be printing name, not &name.

I suggest that you fix your program by #include <string> and using a std::string.

Quote:

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Originally Posted by brack

First of all, i know this code is wrong and i know how to fix it hopefully! However, i do not know why the green point is wrong! I mean that i try to have a char pointer named "name" but...what is going wrong with this?
thanks in advance...

Code:

---

#include <iostream>

using namespace std;

int main(void){
    char *name;
        cout << "name: ";
        cin >> name;
        cout << "your name is: " << &name << "\n";
return 0;
}

---

---

Dude your code is fine, except that you are printing the address of name and not what name points to..

just remember that cin would not store a whitespace character..
so if i enter "John Doe" it would only print John.

Just remove the ampersand from name, and it should be fine..
it worked for me here anyways

Quote:

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Originally Posted by Eman

Dude your code is fine, except that you are printing the address of name and not what name points to..

just remember that cin would not store a whitespace character..
so if i enter "John Doe" it would only print John.

Just remove the ampersand from name, and it should be fine..
it worked for me here anyways

---

you may be right but in dev++ compiler it crushes...

is there a dev++ compiler?

i used a dev c++ here and all it asked was for me to put a newline at the printf function..

Quote:

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Originally Posted by brack

you may be right but in dev++ compiler it crushes...

---

Because your code is not fine.

Quote:

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Just remove the ampersand from name, and it should be fine..
it worked for me here anyways

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It worked because luckily the 'name' pointed to a valid memory location.

As laserlight said:

Quote:

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One problem is that you only have a pointer to char; you don't have any space to actually store a name.

---

You need to allocate memory for name before use. This means changing your

Code:

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char *name;

---

to

Code:

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char name[30];

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or using dynamic memory.

But as laserlight also suggested you would be better off changing to std::string instead of character arrays.


Jim

Quote:

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Originally Posted by kmdv

Because your code is not fine.



It worked because luckily the 'name' pointed to a valid memory location.

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I would use this to refresh my memory on C strings....
so what would be the way to fix it?

to declare
char *name and immediately initialise it to a string?
like so:



Actually, I just used the debugger in Dev C++ and it didn't work, embarrassed here :(


I guess i would have to

Code:

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char *name ="name"  ;

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initialize the pointer on declaration either to a hard coded string or I could do this

Code:

---


#include <iostream>

using namespace std;

int main(void)
{
    char *name ;
    char _name[10] ;
        cout << "name: ";
       
                cin >> _name ;
               
                name = _name ;
               
        cout << "your name is: " << name << "\n";
   
    system("pause") ;
    return 0;
}

---

And that should work.

Quote:

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Originally Posted by Eman

I would use this to refresh my memory on C strings....
so what would be the way to fix it?

---

jimblumberg's example of declaring a 30 character array would be applicable (though the code as it is would then be vulnerable to buffer overflow).

Quote:

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Originally Posted by Eman

to declare
char *name and immediately initialise it to a string?

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No. You cannot change a string literal.

Quote:

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Originally Posted by Eman

or I could do this (...) And that should work.

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The pointer to char named name would also be useless since one could print _name directly.

No. You cannot change a string literal.


yes, I know. but it is still possible to declare a pointer to a string on initialization of the char* pointer and not get a segmentation fault (I am not talking about changing it after).

The pointer to char named name would also be useless since one could print _name directly.[/QUOTE]

lol yeah

Quote:

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Originally Posted by laserlight
jimblumberg's example of declaring a 30 character array would be applicable (though the code as it is would then be vulnerable to buffer overflow).

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I agree about the vulnerability for buffer overflow. This is the case for any Cstring. That is why using std::string is a much better alternative.

Jim

Quote:

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Originally Posted by Eman

Dude your code is fine, except that you are printing the address of name and not what name points to..

just remember that cin would not store a whitespace character..
so if i enter "John Doe" it would only print John.

Just remove the ampersand from name, and it should be fine..
it worked for me here anyways

---

If it worked for you, you got very very unlucky, because this is memory error. The only way it worked for you is that you got "lucky" enough to write over memory that happened to be in your address space