Thread: pointer assignment

i want to know whether this direct assignment to pointer variable is valid or not.
i compiled the program in dev c++ and it works also but i am little bit confused as a pointer variable definition says that it is a variable which holds the address of another variable so is it safe to initialise pointer variables with some values given from cin directly.

Code:

#include<iostream>
#include<conio.h>

using namespace std;
int main()
{
 struct stu
 {
     int size;
     char name[10];
     
 }*ptr=NULL;
 ptr=new stu;
 cin>>ptr->size;
 cin>>ptr->name;
 
 cout<<ptr->size<<ptr->name;
 getch();
 return 0;
}

cin>>ptr->size;
cin>>ptr->name;

These are not pointers, they are an int and a char* actually. And cin operator >> works by reference, so as long as the object exists, it is valid.

to whiteflags:-
can you please explain me in detail. i am new to c and c++

Originally Posted by shikhardeep

to whiteflags:-
can you please explain me in detail. i am new to c and c++

Code:

#include<iostream>
#include<conio.h>

using namespace std;
int main()
{
 struct stu
 {
     int size;
     char name[10];
     
 }*ptr=NULL;
 1. ptr=new stu;
 2. cin>>ptr->size;
 3. cin>>ptr->name;
 
 4. cout<<ptr->size<<ptr->name;
 getch();
 return 0;
}

1. This assigns a new stu object to ptr. If it does not succeed, new will throw an exception.
2. This changes size if the user enters a valid integer. If the user fails to provide a good integer, then cin will enter a bad state, and size remains unchanged.
3. This line works similarly to 2. The only difference is that the input should be a string that fits in name.
4. You echo the int and name back, but it could be garbage.

Steps two and three and four also depend on the success of step 1. The fact that you're using pointers doesn't matter. As I mentioned, cin operator >> works by reference, and as long as the pointer actually points to a stu object, the code will work.

thank u. could u please reccommend me some website,books or weblinks so that i can clear my concepts especially on pointers,self referencial structures and data structures like linked list