From: Randi Botse <nightdecoder@gmail.com>
To: linux-c-programming <linux-c-programming@vger.kernel.org>
Subject: Pointer to a char
Date: Tue, 18 Sep 2012 16:29:32 +0700 [thread overview]
Message-ID: <CAA6iF_7=j6J+wOyYcQgwvSO1dG92kVNcJcYXFY7BiiRZ4d0UKQ@mail.gmail.com> (raw)
Hi, having coding in C for 3 years but I'm still not clear with this one.
Consider this code.
...
char *p;
unsigned int i = 0xcccccccc;
unsigned int j;
p = (char *) &i;
printf("%.2x %.2x %.2x %.2x\n", *p, p[1], p[2], p[3]);
memcpy(&j, p, sizeof(unsigned int));
printf("%x\n", j);
...
Output:
ffffffcc ffffffcc ffffffcc ffffffcc
0xcccccccc
My questions are:
1. Why it prints "ffffffcc ffffffcc ffffffcc ffffffcc"? (if p is
unsigned char* then it will print correctly "cc cc cc cc")
2. Why pointer to char p copied to j correctly, why not every member
in p overflow? since it is a signed char.
Regards.
next reply other threads:[~2012-09-18 9:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-18 9:29 Randi Botse [this message]
2012-09-18 10:29 ` Pointer to a char Phil Sutter
2012-09-18 10:33 ` Duan Fugang-B38611
2012-09-19 1:04 ` Jon Mayo
2012-09-19 7:59 ` Randi Botse
2012-09-19 8:47 ` Leon Shaw
2012-09-19 18:09 ` Jon Mayo
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