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Q&A

Why use an asterisk after a type?

+2
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#include<stdio.h>
struct Node{
     int data;
     struct Node* next;
};

Here I used an asterisk after Node. What is it used for? What if I don't put any asterisk after Node (both Node's are structures)?

Is *ptr and ptr* same?

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1 comment thread

Pointers (3 comments)

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+11
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Here I used asterisk after Node. Actually, why asterisk used for? What if I don't put any asterisk after Node (Both Node are structure).

It's a pointer.

A pointer, like its name implies, points to an actual object in memory. (More technically, it holds an address to the memory location).

In your Node example, it is necessary because using a plain object is impossible.

Think of a struct like a box. The box has compartments, which hold the items in it. By necessity, the compartment must be smaller than the box itself.

Now, imagine trying to stuff a Node into another Node. This is like trying to stuff a box into a compartment of a box of the same size -- it just doesn't fit.

However, if we use a pointer, we get around that problem. We slip in a piece of paper into the box that says "the next box is over there", so we don't try to stuff boxes in boxes.

Is *ptr and ptr* same?

It's not.

The basic syntax to declare a pointer is type * var_name. The most likely confusion you have is which one is the type, and which one is the variable name.

In struct Node * next, struct Node is the type, and next is the variable name.

In int *ptr;, int is the type, and ptr is the variable name.

Note that spaces are completely irrelevant. int* ptr is the same as int *ptr is the same as int * ptr.

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+3
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The * for variables and not mathematical operators are the pointers.

Assigning a pointer goes this way:

char *text; // string

Here, we assign a pointer named text and its type is a char, but alternatively, this is a string.

As for your question, int *ptr is basically the same as int* ptr, only being a pointer of an int, and nothing else. Your given struct Node* next is the same as struct Node *next, and I don't think ptr* even exists, unless it's made as some union or struct. struct *Node wouldn't work likely.

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1 comment thread

Which language did you use? (5 comments)

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