From: ts <decoux@...>
Date: 2006-02-22T19:10:02+09:00
Subject: Re: Question about String.unpack

>>>>> "E" == Eric Hodel <drbrain@segment7.net> writes:

>> My C compiler gives me a total sizeof of 48, so i use a
>> fd.sysread(48).unpack(A32dIC) to re-read. But that seems rather

E> Your struct says char name[30] not 32...

 Yes, but there is alignement

 He just want Z32 rather than A32

biocluster1% cat a.c
#include <stdio.h>
#include <string.h>

typedef struct {
    char name[30];
    double size;
    int age;
    char stuff;
} enreg_t;

main()
{
    FILE *fd;
    enreg_t enreg;
    strcpy(enreg.name, "abc");
    enreg.size = 12.0;
    enreg.age = 12;
    enreg.stuff = 'a';
    fd = fopen("aa", "w");
    fwrite(&enreg, sizeof(enreg), 1, fd);
    fclose(fd);
}
biocluster1% 

biocluster1% ruby -e 'p a = IO::read("aa"); p a.unpack("Z32dIC")'
"abc\000\030\373\377\277U\203\004\010tp\001@\360z\001@8\373\377\277K\205\004\010\200\270\024@\000\000\000\000\000\000(@\f\000\000\000ae\001@"
["abc", 12.0, 12, 97]
biocluster1% 


Guy Decoux