Re: Question about double pointers assignment

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int *temp[5] would be read as "temp is an array of 5 pointers to int
and
int (*temp)[5] would be read as "temp is a pointer to an array of 5 integers.

not sure if you are looking for something else.

Thanks and Regards,
Naveen

Saquib Imam wrote:

Can u tel me the difference between

Int *temp[5];

And

Int (*temp)[5];

Thanks & Regards,

Saquib Imam

------------------------------------------------------------------------

*From:* kernelnewbies-bounce@xxxxxxxxxxxx [mailto:kernelnewbies-bounce@xxxxxxxxxxxx] *On Behalf Of *sahlot arvind
*Sent:* Wednesday, December 26, 2007 10:34 AM
*To:* Saquib Imam
*Cc:* Cihan Kömeçoğlu; C_C_Kuo@xxxxxxxxxxxxxx; kernelnewbies@xxxxxxxxxxxx
*Subject:* Re: Question about double pointers assignment

>#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 <mailto: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> [mailto: 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 <mailto:C_C_Kuo@xxxxxxxxxxxxxx>
*Cc:* kernelnewbies@xxxxxxxxxxxx <mailto: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

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