Brian “Beej Jorgensen” Hall gives in his Guide to Network Programming some code to pack float (resp. double) to uint32_t (resp. uint64_t) to be able to safely transmit it over the network between two machine that may not both agree to their representation. It has some limitation, mainly it does not support NaN and infinity. … Read more
Use if (WIN32) #do something endif (WIN32) or if (UNIX) #do something endif (UNIX) or if (MSVC) #do something endif (MSVC) or similar see CMake Useful Variables and CMake Checking Platform
Since a great part of writing software is about reusing existing solutions, the first thing should always be a look into the documentation for your language/library. reverse = Integer.reverseBytes(x); I don’t know how efficient this function is, but for toggling lots of numbers, a ByteBuffer should offer decent performance. import java.nio.ByteBuffer; import java.nio.ByteOrder; … int[] … Read more
#define htonll(x) ((1==htonl(1)) ? (x) : ((uint64_t)htonl((x) & 0xFFFFFFFF) << 32) | htonl((x) >> 32)) #define ntohll(x) ((1==ntohl(1)) ? (x) : ((uint64_t)ntohl((x) & 0xFFFFFFFF) << 32) | ntohl((x) >> 32)) The test (1==htonl(1)) simply determines (at runtime sadly) if the hardware architecture requires byte swapping. There aren’t any portable ways to determine at compile-time what … Read more
It is not safe per the C++ standard. As stated in this SO posting: A C callback function implemented in C++ must be extern “C”. It may seem to work as a static function in a class because class-static functions often use the same calling convention as a C function. However, doing that is a … Read more
The chdir function works on both POSIX (manpage) and Windows (called _chdir there but an alias chdir exists). Both implementations return zero on success and -1 on error. As you can see in the manpage, more distinguished errno values are possible in the POSIX variant, but that shouldn’t really make a difference for most use … Read more
The order of evaluation of subexpressions, including the arguments of a function call and operands of operators (e.g., +, -, =, * , /), with the exception of: the binary logical operators (&& and ||), the ternary conditional operator (?:), and the comma operator (,) is Unspecified For example int Hello() { return printf(“Hello”); /* … Read more
Personally I’d go with the option of not using placement new on the array and instead use placement new on each item in the array individually. For example: int main(int argc, char* argv[]) { const int NUMELEMENTS=20; char *pBuffer = new char[NUMELEMENTS*sizeof(A)]; A *pA = (A*)pBuffer; for(int i = 0; i < NUMELEMENTS; ++i) { … Read more
The function getenv is the only one specified by the C standard. The function putenv, and the extern environ are POSIX-specific. EDIT The main parameter envp is not specified by POSIX but is widely supported. An alternative method of accessing the environment list is to declare a third argument to the main() function: int main(int … Read more
You can use z for size_t and t for ptrdiff_t like in printf(“%zu %td”, size, ptrdiff); But my manpage says some older library used a different character than z and discourages use of it. Nevertheless, it’s standardized (by the C99 standard). For those intmax_t and int8_t of stdint.h and so on, there are macros you … Read more