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Re: "sizeof" get unwanted result

From: "Kevin P. Fleming" <kpfleming at starnetworks dot us>
Cc: gcc-help at gcc dot gnu dot org
Date: Mon, 18 Apr 2005 22:03:18 -0700
Subject: Re: "sizeof" get unwanted result
Organization: Star Networks, LLC
References: <WorldClient-F200504191048.AA48130048@insun.hit.edu.cn>

Xiaoshan Sun wrote:

   i use "sizeof" to get the size of a struct ,defined as:
   typedef struct _A {
     long data1;
     unsigned short data2;
     long  data3;
   }A;
 i guess the sizeof(A) should be 10 .however when i compile and print the
value of "sizeof(A)" ,the reult is 12!!

That's exactly to be expected, on any 32-bit platform. It could be even larger on a 64-bit platform.

If you don't use the 'packed' attribute, the layout and alignment of the structure is entirely implementation-dependent.

References:
- "sizeof" get unwanted result
  - From: Xiaoshan Sun

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