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How to input 8 byte hexadecimal number into char array?

Answer 1

+2 A:

What are you using to print out your value? The syntax for printing 8 0-padded bytes to stdout would be something like

printf("%016X", value);

It breaks down like this:

%x    = lowercase hex
%X    = uppercase hex
%16X  = always 16 characters (adds spaces)
%016X = zero-pad so that the result is always 16 characters

For example, you could do the same thing in base 10:

printf("%05d", 3); // output: 00003

You can also play with decimals:

printf("%.05f", 0.5); // output: 0.50000

http://www.cplusplus.com/reference/clibrary/cstdio/printf/

Kelsey Rider 2010-08-19 11:16:55

No i wanted to know how can store my initial value 0x0706050403020100.can i store it using character array or dynamically using malloc or using unsigned long long int ??

Thej 2010-08-19 11:20:25

You can store your value anywhere where you've allocated at least 8 bytes of memory. This could be a long (depending on the hardware), a char[8], a long double (which might actually be 16 bytes), a struct that you make, etc.In your initial post you said your problem was that you don't see the first hex character when you output your number. This is normal - it's just like, when you output the value 3, you often don't want to see 0000000003. If you want leading zeroes, you have to tell printf to include them. But I can assure you that your machine has not "forgotten" about a nybble.

Kelsey Rider 2010-08-19 11:34:20

I also might add that doingchar[8]="0x0706050403020100";will probably produce a segfault, because you're declaring 8 bytes and filling it with 18.

Kelsey Rider 2010-08-19 11:40:18

@Rider:Thanks.But hw to tell printf to include leading zeroes.

Thej 2010-08-19 11:43:10

So how should i declare using char(static or dynamically)??

Thej 2010-08-19 11:44:26

To show leading zeroes, use printf like I showed you. :)I'll edit my original post to be more specific.

Kelsey Rider 2010-08-19 14:44:09

I was just mentioning the char array as an example, but I doubt that a char array is the optimal solution. If you really want to use a char array, declare your char arr[8], then read your 8-byte value into the memory pointed to by arr. To print it, you'd then have to either loop over each char, printing each one as a zero-padded 2-digit hex value, or else cast arr as a (long *). Depending on the hardware, you may have issues like endianness to deal with. Like I said, probably not your ideal solution. :)

Kelsey Rider 2010-08-20 07:01:46

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How to input 8 byte hexadecimal number into char array?

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