Re: Question about double pointers assignment

["sahlot arvind" <asahlot@xxxxxxxxx>]

>#include<stdio.h>

>#include<stdlib.h>

>int    exterint[5][5];

>int    exterint1[5];

>int main(void){

>int index0, index1;

>int **temp1;

>int *temp2;

>temp2=exterint1; //*****

>temp1 = exterint;  //xxxxxxxxx

>The compiler will warn me that at line marked as xxxxx is "assignment from incompatible pointer type."

> But "******" doesn't get any warning.

Here exterint1 is a pointer to the first element of one dimensional array, which is nothing but an integer. Thus "exterint1" is nothing but simply a pointer  to an integer. Thats why you can assign it "temp2" which is also a pointer of same type.

But keeping in mind the way two dimensional arrays are treated, "exterint" is a pointer to an array of integers of size 5. Note that it is not a pointer to pointer to an integer, while "temp1" is a pointer to pointer to integer. Thus when in "temp1 = exterint" the assignment is not correct and hence warning.

To remove it what you can do it, declare "temp1" as a pointer to an array of integer of size 5. Something like this -

 

int (*temp1)[5];

temp1 = externint;

 

Hope it helps.

 

Best regards

Arvind Sahlot

 

On 12/26/07, Saquib Imam <saquib.imam@xxxxxxxxx> wrote:

…

int    exterint[5][5];

int    exterint1[5];

…

int **temp1;

int *temp2;

….

temp2=exterint1; //*****

temp1 = exterint;  //xxxxxxxxx    "ERROR GIVING LINE"

 

In the above case exterint1 will be pointing to the first element of the integer array, so it can be assigned to a integer pointer.

 

So the assignment

temp2=exterint1;   is correct.

 

While in case of exterint , it will be pointing to the first element to the first row , again its pointing to a integer not a pointer to the integer while temp1 is a pointer to the pointer to an integer.

 

So the assignment  

 temp1 = exterint   gives an error.

Thanks & Regards,

Saquib Imam

---

From: kernelnewbies-bounce@xxxxxxxxxxxx [mailto: kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf Of Cihan Kömeçoglu
Sent: Monday, December 24, 2007 4:26 PM
To: C_C_Kuo@xxxxxxxxxxxxxx
Cc: kernelnewbies@xxxxxxxxxxxx
Subject: Re: Question about double pointers assignment

 

I think , the problem is there

 

temp1 = exterint

 

temp1 is pointer to pointer,not pointer to int but you assigned adress of exterint1 and this array of integer; not array of pointer.

For example like this give you same warning:

 

int * temp1;

int a;

temp1 = a; 

Warrning:"assignment from incompatible pointer type

 

This is correct if you do like below

 

int *temp1

int exterint[5];

 

temp1 = exterint;

 

Monday, December 24, 2007, 11:49:37 AM, you wrote:

 

>

Dear all: I write a program like below:   #include<stdio.h> #include<stdlib.h> int    exterint[5][5]; int    exterint1[5]; int main(void){     int index0, index1;     int **temp1;     int *temp2;     temp2=exterint1; //*****     temp1 = exterint;  //xxxxxxxxx ….. …..}   The compiler will warn me that at line marked as xxxxx is "assignment from incompatible pointer type." But "******" doesn't get any warning.   Is there any restriction about assigning multi-layer array or something about pointer I miss?   Appreciate your help, cckuo   ***************** 　 Novatek Email Confidentiality Notice ***************** The information contained in this electronic communication, and any electronic attachments, is confidential or legally privileged and may be subject to protection under the law. It is intended only for the named recipient above. If you have received this communication in error, or are not the named recipient, please immediately notify the sender via reply email and delete this communication from your computer system, and destroy all copies of this communication along with any attachments. Thank you for your cooperation.   Copyright Novatek 2006-2007 All Rights Reserved

 

 

 

 

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