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 8.1.1, “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 0x
or
value
X'
format.
However, the return value does not include the
value
'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 is this",12); 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.
User Comments
Inside your description:
The return value is the length of the encoded string, not including the terminating null character.<--This says the return value of the function is the "length of the encoded string"
Inside the next paragraph:
The return value can be placed into an SQL statement using either 0xvalue or X'value' format.<--Is this return value the same one as which mention in the preceding paragraph? I am being confused. If it is the same, that means my SQL statment will be something like "insert blahblahblah value (0xlengthbeingreturn). Is this what you mean? Or what you really saying is 0xToString?
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