TT.
2020-03-18 02:08:57
You need to sum every byte in the message up to but not including the checksum field. Then take this number modulo 256, and print it as a number of 3 characters with leading zeroes (e.g. checksum=13 would become 013).
Link from the FIX wiki: FIX checksum
An example implementation in C, taken from onixs.biz:
char *GenerateCheckSum( char *buf, long bufLen )
{
static char tmpBuf[ 4 ];
long idx;
unsigned int cks;
for( idx = 0L, cks = 0; idx < bufLen; cks += (unsigned int)buf[ idx++ ] );
sprintf( tmpBuf, "%03d", (unsigned int)( cks % 256 ) );
return( tmpBuf );
}
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"sum every byte in the message". Can you write it in this case?
I still dont understand that example. I write c#. If I have a FixMessage: {8=FIX.4.29=4935=534=149=ARCA52=20150916-04:14:05.30656=TW10=157}. How to count it to 157?
@ANguyen Quickfix is a library that can produce a FIX message for you. A FIX message is a string consisting of ASCII characters. To calculate the checksum, 1/ each byte in the message up to the checksum field is summed 2/ take the modulo 256 of that sum 3/ print that number as a number of 3 characters with leading zeros. I can't say it simpler that that. You can't simply dump a FIX message here and expect us to count it for you. You ask the QuickFIX library or any other FIX engine to do it for you.
@ANguyen For me it's been too long since I've done any C# coding, and I'm not proficient with QuickFIX/N. Look into converting a string to a byte stream or byte-array (ASCII encoding). Sum each byte in the array or stream to an unsigned int. Then take the modulo 256 of the total and print it as a 3 character string with leading zeroes.
When I compile that example C program and use the wiki page test case, it gives me 70, not 65 as wiki says