[freetds] Convert Hexadecimal To String

Discussion:

Velichko Yuriy

2013-09-24 17:25:31 UTC

Hello!

I use method dbdata() to get data returned by dbsqlexec().
To fetch binary data I use dbconvert() to convert data into SYBCHAR.
This method gives the hexadecimal string.

Can you suggest me how to convert this string to character string?

For example MySQL client has build-in method for this purpose:
mysql_hex_string();

freetds (dblib) has something similar?

Thanks!

--
Best Regards!

John Boia

2013-09-24 18:49:25 UTC

Permalink

Try this. I found it elsewhere and augmented it.

std::string bin_to_hex( const unsigned char *input, size_t len )
{
static const char* const lut = "0123456789ABCDEF";

// Convert each byte to 2-char hex representation
std::string output;
output.reserve(2 * len);
volatile unsigned char c;
for (size_t i = 0; i < len; ++i)
{
c = input[i];
output.push_back(lut[c >> 4]);
output.push_back(lut[c & 15]);
}

// Trim excess nulls from end of binary string
bool done = false;
while( !done ) {
size_t pos = output.rfind("0000000000000000");
if ( pos != std::string::npos ) {
output.erase(pos,16);
} else {
done = true;
}
}

return output;
}

Post by Velichko Yuriy
Hello!
I use method dbdata() to get data returned by dbsqlexec().
To fetch binary data I use dbconvert() to convert data into SYBCHAR.
This method gives the hexadecimal string.
Can you suggest me how to convert this string to character string?
mysql_hex_string();
freetds (dblib) has something similar?
Thanks!
--
Best Regards!
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Velichko Yuriy

2013-09-24 19:06:17 UTC

Permalink

Thanks!

Post by John Boia
Try this. I found it elsewhere and augmented it.
std::string bin_to_hex( const unsigned char *input, size_t len )
{
static const char* const lut = "0123456789ABCDEF";
// Convert each byte to 2-char hex representation
std::string output;
output.reserve(2 * len);
volatile unsigned char c;
for (size_t i = 0; i < len; ++i)
{
c = input[i];
output.push_back(lut[c >> 4]);
output.push_back(lut[c & 15]);
}
// Trim excess nulls from end of binary string
bool done = false;
while( !done ) {
size_t pos = output.rfind("0000000000000000");
if ( pos != std::string::npos ) {
output.erase(pos,16);
} else {
done = true;
}
}
return output;
}