fread / fwrite可以把資料以binary的形式寫入file,
所以用來讀寫struct是再好不過,
記得注意big-endian / little-endian的問題即可

分別在ccsun, ccbsd執行fread.c看看 :)

chlo@ccbsd1 [1:07pm] ~> echo 84148993 | ./fwrite > tout
1 3 4 5
chlo@ccbsd1 [1:08pm] ~> ./fread < tout
84148993
1 3 4 5

{chlo@ccsun1}~> gcc fread.c -o fread_sun
{chlo@ccsun1}~> ./fread_sun < tout
16974853
1 3 4 5

source:

fwrite.c:

#include <stdio.h>

typedef struct {
        int n;
} Num;

int main(void)
{
        Num a;
        int i;
        char *s;

        scanf("%d", &a.n);
        fwrite(&a, sizeof(a), 1, stdout);

        s = (char*)&a.n;
        for (i=0; i<4; i++)
                fprintf(stderr, "%u ", s[i]%256);
        fprintf(stderr, "\n");
        return 0;
}

fread.c:

#include <stdio.h>

typedef struct {
        int n;
} Num;

int main(void)
{
        Num a;
        int i;
        char *s;

        fread(&a, sizeof(a), 1, stdin);
        printf("%d\n", a.n);

        s = (char*)&a.n;
        for (i=0; i<4; i++)
                fprintf(stderr, "%u ", s[i]%256);
        fprintf(stderr, "\n");
        return 0;
}