From mboxrd@z Thu Jan  1 00:00:00 1970
From: Randi Botse <nightdecoder@gmail.com>
Subject: Re: Pointer to a char
Date: Wed, 19 Sep 2012 14:59:40 +0700
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To: linux-c-programming <linux-c-programming@vger.kernel.org>

Hi Phil, Jon

Thanks, now I'm clear with this, assignment doesn't care with type modifier.

Code such as

unsigned int j = 0xffeeddcc;
int i = j;

Both has the same value depending on how them interpreted (is this
assumption correct?)

Because,

printf("%u", i) will be different to printf("%i", i)
- but -
printf("%u", i) wlll be same as printf("%u", j)


Actually why asking this because I often see a pointer to a char* cast

Let me show you with this example.
Consider some structures...

struct a_data {
    unsigned char f1[4];
    unsigned char f2[6];
    unsigned short f3[2];
};

and another struct named b_data, c_data, etc.

Then there is a general function to process all type of structure,
maybe something like this:

int process_data(char *buffer, size_t len);

Then if we cast for example a pointer to a_data struct to a char* as follow:

struct a_data a;
process_data((char*) &a, sizeof(a));

I though since it was cast to char*, the cast is "problem" because
every signed char buffer will have a range CHAR_MIN to CHAR_MAX,
therefore value of CHAR_MAX to UCHAR_MAX will broken (signed char
overflow)

I think process_data() should be declared with

int process_data(unsigned char *buffer, size_t len)

this declaration in seem correct and work for me.

However, now I'm conceptually understand why this works.

Thanks.