Re[2]: Question about double pointers assignment

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Int *temp[5]; this is pointer array that each element of array stores pointer.

Int (*temp)[5]; this is integer array but temp is pointer and this point to integer array not pointer array.


Wednesday, December 26, 2007, 8:07:07 AM, you 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> 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@xxxxxxxxxxxxOn 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

 

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-- 

Cihan Kömeçoğlu,

EnderUNIX SDT                           mailto:cihan@xxxxxxxxxxxxx

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