Frama-C One thing has been peeving me for a while. It is small and does not impact me directly, so I didn't speak up, but perhaps I should. Many people, some of whom should know better, mention Floyd, Hoare and Dijkstra in the same sentence as modern verification condition generators (Frama-C's...
Read MoreSpeaking of John Carmack, in his twitter feed, he notes: In hindsight it is surprising that I disliked doing math proofs in high school despite already being a programmer. It says a lot about the French education system that I started teaching myself programming at 6 and officially switched from...
Read MoreMy colleague Bernard Botella pointed out an interesting example in an offline discussion following the last quiz. The setup Consider the snippet: int s; unsigned u1 u2; ... s = u1 - u2; The programmer's intention with the assignment is to compute in variable s of type int the mathematical...
Read MoreThere are only positive constants in C, as per section 6.4.4 in the C99 standard: integer-constant: decimal-constant integer-suffixopt octal-constant integer-suffixopt hexadecimal-constant integer-suffixopt decimal-constant: nonzero-digit decimal-constant digit octal-constant: 0 octal-constant octal-digit hexadecimal-constant: hexadecimal-prefix hexadecimal-digit hexadecimal-constant hexadecimal-digit ... The minus sign is not part of the constant according to the grammar. The...
Read MoreWhat does the following program print? long long l; #include <stdio.h> int main() { l = -0x80000000; printf(\%lld" l); } $ gcc t.c && ./a.out And this one? (beware trick question) long long l; #include <stdio.h> int main() { l = -2147483648; printf("%lld" l); } $ gcc t.c && ./a.out...
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