Re: Help with char to hex.

"Victor Bazarov" <>
Mon, 20 Nov 2006 16:42:56 -0500
<ejt7h1$c4d$> wrote:

Hello, I'm working with sockets and I'm having some trouble. I need to
convert each char in a char array to hex but I can't seem to get it
working right.

I know the true bytes I'm received is "BF 00 06 00 24 3A" however if I
do something like this;

char pBuf[64];
char hex[3];

for(int i = 0; i < len; i++)
sprintf(hex, "%X ", (signed int)buf[i]);

Unless you know what you're doing, you should NOT use 'sprintf'. Your
buffer ('hex' array) is not nearly long enough to contain the output.
You might want to read up on field width modifiers for formatted output.
Like using %02X instead of %X. Still, your 'hex' *has to* be longer.

strcat(pBuf, hex);

I get this in pBuf "FFBF FFFFFFBF F0 6 0 24 3A" which I don't feel is
correct. I'm received 6 bytes (well 6 chars according to recv(SOCKET,
char*, int, int)).

I'd like to find out how I can take the chars I'm receiving and
convert them to "BF 00 06 00 24 3A".

Use 'std::string' and 'std::ostringstream'. And you really don't need
'ostringstream'. Conversion of a byte (an unsigned char) to hex is
very simple:

    static const char hexchars[] = "0123456789ABCDEF";
    char hex[4] = {};
    hex[0] = hexchars[(my_unsigned_char >> 4) & 0xf];
    hex[2] = hexchars[my_unsigned_char & 0xf];
    hex[3] = ' ';

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