CODEWITHSUNDEEP
cgccgcc-warning
thetna
thetna

Reputation: 7143

Getting the warning "cast to pointer from integer of different size" from the following code

The code is:

           Push(size, (POINTER)(GetCar(i) == term_Null()? 0 : 1));

Here is the C code push returns ABC which is 

 typedef POINTER  *ABC
 typedef void * POINTER
 ABC size;
 Push(ABC,POINTER);
 XYZ GetCar(int);
 typedef struct xyz *XYZ;
 XYZ term_Null(); 
 long int i;

What is the reason for the particular warning?

Upvotes: 9

Views: 22305

Answers (4)

anatolyg
anatolyg

Reputation: 28239

You can use intptr_t to ensure the integer has the same width as pointer. This way, you don't need to discover stuff about your specific platform, and it will work on another platform too (unlike the unsigned long solution).

#include <stdint.h>

Push(size, (POINTER)(intptr_t)(GetCar(i) == term_Null()? 0 : 1));

Taken from the C99 Standard:

7.18.1.4 Integer types capable of holding object pointers

1 The following type designates a signed integer type with the property that any valid pointer to void can be converted to this type, then converted back to pointer to void, and the result will compare equal to the original pointer:

intptr_t

Upvotes: 21

orlp
orlp

Reputation: 117641

What are you trying to do? Pointers are not integers, and you are trying to make a pointer out of 0 or 1, depending on the situation. That is illegal.

If you were trying to pass a pointer to a ABC containing 0 or 1, use this:

ABC tmp = GetCar(i) == term_Null()? 0 : 1;
Push(size, &tmp);

Upvotes: 0

Bob Prystanek
Bob Prystanek

Reputation: 441

Since this question uses the same typedefs as your 32bit to 64bit porting question I assume that you're using 64 bit pointers. As MByd wrote you're casting an int to a pointer and since int isn't 64 bit you get that particular warning.

Upvotes: 0

MByD
MByD

Reputation: 137272

You are trying to cast an integer value (0 or 1) to a void pointer.

This expression is always an int with value 0 or 1: (GetCar(i) == term_Null()? 0 : 1)

And you try casting it to void pointer (POINTER) (typedef void * POINTER).

Which is illegal.

Upvotes: 0

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