25.2.3.33. mysql_hex_string()
unsigned long mysql_hex_string(char *to, const char
*from, unsigned long length)
Description
This function is used to create a legal SQL string that you
can use in an SQL statement. See
Section 9.1.1, “Strings”.
The string in from is encoded to
hexadecimal format, with each character encoded as two
hexadecimal digits. The result is placed in
to and a terminating null byte is appended.
The string pointed to by from must be
length bytes long. You must allocate the
to buffer to be at least
length*2+1 bytes long. When
mysql_hex_string() returns, the contents of
to is a null-terminated string. The return
value is the length of the encoded string, not including the
terminating null character.
The return value can be placed into an SQL statement using
either 0xvalue
or X'value'
format. However, the return value does not include the
0x or X'...'. The caller
must supply whichever of those is desired.
Example
char query[1000],*end;
end = strmov(query,"INSERT INTO test_table values(");
end = strmov(end,"0x");
end += mysql_hex_string(end,"What's this",11);
end = strmov(end,",0x");
end += mysql_hex_string(end,"binary data: \0\r\n",16);
*end++ = ')';
if (mysql_real_query(&mysql,query,(unsigned int) (end - query)))
{
fprintf(stderr, "Failed to insert row, Error: %s\n",
mysql_error(&mysql));
}
The strmov() function used in the example
is included in the mysqlclient library and
works like strcpy() but returns a pointer
to the terminating null of the first parameter.
Return Values
The length of the value placed into to, not
including the terminating null character.
Errors
None.
