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Postings from January 2008
On Jan 18, 2008, at 6:55 PM, Dave Rolsky wrote:
> People always talk about boundary alignments, and other gibberish.
http://en.wikipedia.org/wiki/Data_structure_alignment
Here's an example of an alignment problem:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int main() {
int foo = 1000;
char *bar = (char*)malloc( sizeof(int) + 1 );
char *bar_plus_one = bar + 1;
int baz;
memcpy(bar_plus_one, &foo, sizeof(int));
baz = *(int*)bar_plus_one; /* boom? */
printf("%d\n", baz);
return 0;
}
bar_plus_one isn't word-aligned. That code will work on some
systems, but not others.
Marvin Humphrey
Rectangular Research
http://www.rectangular.com/
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