WebApp Sec mailing list archives
Re: modulo question
From: Michael Vergoz <descript () secureyourapache com>
Date: Tue, 19 Apr 2005 09:59:09 +0400
Hello, --1 will decrement and is not negative. descript-mac:~ descript$ cat > test.c int main() { printf("%d", --1); } descript-mac:~ descript$ cc -o test test.c test.c: In function `main': test.c:2: error: invalid lvalue in decrement and is invalid. Using modulo with negative numbers ?! 0xFEBA3245-(0xFEBA3245%0x1000) = 4K aligned page. descript-mac:~ descript$ cat > test.c int main() { long plof = 0xFEBA3245; printf("Number : %lx(%ld)\n", plof, plof); printf("4Ko alignement: %lx\n", plof-(plof%0x1000)); } descript-mac:~ descript$ cc -o test test.c descript-mac:~ descript$ ./test Number : feba3245(-21351867) 4Ko alignement: feba4000 sya On 15 avr. 05, at 12:47, martin wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello list,I have slightly academic question about modulo. I sent this message here because I thing there are many of gurus which working with modulo operator.I have tried in python and in C++ following: python C++ 1%2 1 1 - -1%2 1 -1 1%-2 -1 1 - -1%-2 -1 -1 What is right? Do you know some applications which using modulo with negative numbers?Have you some references to definition (mathematical def. and properties) ofmodulo? Thanks in advance, Martin -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (GNU/Linux) iD8DBQFCX4Bc9w5olJf0Oq8RAsvSAKCnvAdrdXBL/aqiSTCANjT2BKb7NACcCCel 7b+pYp0k/1hMQPOyAY2M5/4= =zLC1 -----END PGP SIGNATURE-----
Current thread:
- modulo question martin (Apr 18)
- Re: modulo question Michael Vergoz (Apr 20)
- Re: modulo question Skip Carter (Apr 20)
- Re: modulo question Scovetta Labs (Apr 20)
- Re: modulo question Federico CastaƱeda (Apr 20)
- Re: modulo question Kelly John Rose (Apr 20)
- Re: modulo question warnings (Apr 21)