• Oliver (37/37) Feb 19 2011 Hello,
• bearophile (35/36) Feb 19 2011 struct Ts {
• Oliver (4/39) Feb 19 2011 Thanks for the comments.
• Stewart Gordon (13/30) Feb 19 2011 The code you've posted throws an AV, and correctly so. If you change ts...
• oliver (8/41) Feb 19 2011 a ts, it

Oliver <oliver.ruebenkoenig web.de> writes:

Hello,

I have the following code that works. I'd like to change the t tsData to ts
tsData, but this does segfault. I do not understand how I dereferece the ts
struct correctly. Perhaps someone could give me a hint. Thanks.
Oliver

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

alias rs *r;
alias ts *t;

struct ts {
    int d;
    union {
        int[] intData;
        double[] doubleData;
    }
}

struct rs {
    int i;
    union {
        int intData;
        //ts tsData;
        t tsData;
    };

    this( int i, int d, ref int[] data) {
        this.i = i;
        this.tsData.d = d;
        this.tsData.intData = data;
    }
}

r makeData(int i, int d, int[] data) {
    return new rs(i,d,data);
}

int main () {

    int i = 1;
    int[] data = [1,2];
    auto test = makeData(i,1,data);

    return 0;
}

bearophile <bearophileHUGS lycos.com> writes:

Oliver:

 ...

struct Ts {
    int d;
    
    union {
        int[] intData;
        double[] doubleData;
    }
}

struct Rs {
    int i;

    union {
        int intData;
        Ts* tsData;
    }

    this(int i, int d, int[] data) {
        this.i = i;
        this.tsData = new typeof(*tsData);
        this.tsData.d = d;
        this.tsData.intData = data;
    }
}

Rs* makeData(int i, int d, int[] data) {
    return new Rs(i, d, data);
}

void main () {
    int i = 1;
    int[] data = [1, 2];
    auto test = makeData(i, 1, data);
}


- You have not created the pointed inner struct.
- Don't use aliases like those ones, they confuse the code.
- Struct names are better with a starting uppercase letter in D.

Bye,
bearophile

Oliver <oliver.ruebenkoenig web.de> writes:

== Quote from bearophile (bearophileHUGS lycos.com)'s article
 Oliver:
 ...

 struct Ts {
     int d;
     union {
         int[] intData;
         double[] doubleData;
     }
 }
 struct Rs {
     int i;
     union {
         int intData;
         Ts* tsData;
     }
     this(int i, int d, int[] data) {
         this.i = i;
         this.tsData = new typeof(*tsData);
         this.tsData.d = d;
         this.tsData.intData = data;
     }
 }
 Rs* makeData(int i, int d, int[] data) {
     return new Rs(i, d, data);
 }
 void main () {
     int i = 1;
     int[] data = [1, 2];
     auto test = makeData(i, 1, data);
 }
 - You have not created the pointed inner struct.

Yes, thanks, I got it.

 - Don't use aliases like those ones, they confuse the code.
 - Struct names are better with a starting uppercase letter in D.
 Bye,
 bearophile

Thanks for the comments.
Olier

Stewart Gordon <smjg_1998 yahoo.com> writes:

On 19/02/2011 13:18, Oliver wrote:
 Hello,

 I have the following code that works.

What?  The code you've posted doesn't work.

 I'd like to change the t tsData to ts tsData, but this does segfault.

The code you've posted throws an AV, and correctly so.  If you change tsData to
a ts, it 
runs successfully.  At least in 2.051 Windows.  Is something different
happening on your 
setup?

 I do not understand how I dereferece the ts struct correctly.

You don't dereference a struct, you dereference a pointer.

<snip>
 struct rs {
      int i;
      union {
          int intData;
          //ts tsData;
          t tsData;
      };

      this( int i, int d, ref int[] data) {
          this.i = i;
          this.tsData.d = d;
          this.tsData.intData = data;
      }
 }

<snip>

You have not initialised tsData.  Consequently, you are trying to dereference a
null 
pointer.  Hence the segfault.

For it to work with tsData being a pointer, you need to add something like this:

     this.tsData = new ts;

Stewart.

oliver <oliver.ruebenkoenig web.de> writes:

== Quote from Stewart Gordon (smjg_1998 yahoo.com)'s article
 On 19/02/2011 13:18, Oliver wrote:
 Hello,

 I have the following code that works.

 What?  The code you've posted doesn't work.

Sorry for that, in the post I got the // and the second one mixed up.

 I'd like to change the t tsData to ts tsData, but this does segfault.

 The code you've posted throws an AV, and correctly so.  If you change tsData to

a ts, it
 runs successfully.  At least in 2.051 Windows.  Is something different
happening

on your
 setup?

No, no that was a mixup on my side.

 I do not understand how I dereferece the ts struct correctly.

 You don't dereference a struct, you dereference a pointer.

Yea, well that sould have read dereference the pointer to the struct.

 <snip>
 struct rs {
      int i;
      union {
          int intData;
          //ts tsData;
          t tsData;
      };

      this( int i, int d, ref int[] data) {
          this.i = i;
          this.tsData.d = d;
          this.tsData.intData = data;
      }
 }

 <snip>
 You have not initialised tsData.  Consequently, you are trying to dereference
a null
 pointer.  Hence the segfault.
 For it to work with tsData being a pointer, you need to add something like
this:
      this.tsData = new ts;

Thanks, that was what I did not get - for what ever reason - which seems
obvious now.

Oliver

 Stewart.