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Answer 1

+3 A:

Well, if you interpret an integer as a char in C, you'll get that ASCII character, as long as it's in range.

int i = 97;
char c = i;

printf("The character of %d is %c\n", i, c);

Prints:

The character of 97 is a

Note that no error checking is done - I assume 0 <= i < 128 (ASCII range).

Otherwise, an array of byte values can be directly interpreted as an ASCII string:

char bytes[] = {97, 98, 99, 100, 101, 0};

printf("The string: %s\n", bytes);

Prints:

The string: abcde

Note the last byte: 0, it's required to terminate the string properly. You can use bytes as any other C string, copy from it, append it to other strings, traverse it, print it, etc.

Eli Bendersky 2010-04-02 08:49:44

The integer does not have to be `0 <= i < 128` or (`32 <= i < 128` for printable chars). If you convert an integer to a character, the integer is truncated to the 8 LSBs (least significant bits). Only those have to be in the range. E.g. `i = 1121` gives the same result as `i = 97` (`1121 = 1024 + 97`)

Felix Kling 2010-04-02 09:11:37

@Felix: true, but then it doesn't make much sense since you get the modulo 256 of the `int`, which is unlikely to be the desire of the programmer.

Eli Bendersky 2010-04-02 09:27:50

Nitpick: `'a'` may or may not be 97 in C. On most computers today, it is, but the C standard doesn't guarantee this. To do this portably, one has to make a lookup table. Of course, `'a' == 97` is true on most of the systems today.

Alok 2010-04-02 09:33:57

Hi, I meant how I can convert bytes to ASCII and store those values, maybe in an array?

darkie15 2010-04-02 21:08:20

@darkie15: I don't understand what you mean by that. Care to elaborate (or maybe update the question with an example)??

Eli Bendersky 2010-04-03 05:02:35

Okie ... Now hex form can be achieved by using %x format. But this is only for printing .. I want to store that hex form, say in a array .. so i can use it later for more processing.

darkie15 2010-04-05 22:36:14

@darkie15: how about `sprintf` (or `snprintf` then?

Eli Bendersky 2010-04-06 03:21:45

Answer 2

A:

Char.s and Int.s are stored in binary in C. And can generally be used in place of each other when working in the ASCII range.

int i = 0x61;
char x = i;

fprintf( stdout, "%c", x );

that should print 'a' to the screen.

Mimisbrunnr 2010-04-02 08:56:22

Do you want to say that characters are integers?

Felix Kling 2010-04-02 09:04:45

Actually no I don't because that is wrong, they are not. They are generally of different size (byte versus word) however you can treat characters as if they were integers and vice versa.

Mimisbrunnr 2010-04-02 16:54:11

Answer 3

+1 A:

First of all you should take some more care on the formulation of your questions. It is hard to say what you really want to hear. I think you have some binary blob and want it in a human readable form, e.g. to dump it on the screen for debugging. (I know I'm probably misinterpreting you here).

You can use snprintf(buf, sizeof(buf), "%.2x", byte_array[i]) for example to convert a single byte in to the hexadecimal ASCII representation. Here is a function to dump a whole memory region on the screen:


void
hexdump(const void *data, int size)
{
    const unsigned char *byte = data;

    while (size > 0)
    {
        size--;
        printf("%.2x ", *byte);
        byte++;
    }
}

quinmars 2010-04-02 12:38:35

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Conversion from Byte to ASCII in C

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