I would prefer it – vec.begin() precisely for the opposite reason given by Naveen: so it wouldn’t compile if you change the vector into a list. If you do this during every iteration, you could easily end up turning an O(n) algorithm into an O(n^2) algorithm. Another option, if you don’t jump around in the … Read more
C++11 #include <thread> //may return 0 when not able to detect const auto processor_count = std::thread::hardware_concurrency(); Reference: std::thread::hardware_concurrency In C++ prior to C++11, there’s no portable way. Instead, you’ll need to use one or more of the following methods (guarded by appropriate #ifdef lines): Win32 SYSTEM_INFO sysinfo; GetSystemInfo(&sysinfo); int numCPU = sysinfo.dwNumberOfProcessors; Linux, Solaris, AIX … Read more
Stack allocation is much faster since all it really does is move the stack pointer. Using memory pools, you can get comparable performance out of heap allocation, but that comes with a slight added complexity and its own headaches. Also, stack vs. heap is not only a performance consideration; it also tells you a lot … Read more
You have to understand the forwarding problem. You can read the entire problem in detail, but I’ll summarize. Basically, given the expression E(a, b, … , c), we want the expression f(a, b, … , c) to be equivalent. In C++03, this is impossible. There are many attempts, but they all fail in some regard. … Read more
C++ compilation A compilation in C++ is done in 2 major phases: The first is the compilation of “source” text files into binary “object” files: The CPP file is the compiled file and is compiled without any knowledge about the other CPP files (or even libraries), unless fed to it through raw declaration or header … Read more
typedef is a language construct that associates a name to a type. You use it the same way you would use the original type, for instance typedef int myinteger; typedef char *mystring; typedef void (*myfunc)(); using them like myinteger i; // is equivalent to int i; mystring s; // is the same as char *s; … Read more
Position Independent Code means that the generated machine code is not dependent on being located at a specific address in order to work. E.g. jumps would be generated as relative rather than absolute. Pseudo-assembly: PIC: This would work whether the code was at address 100 or 1000 100: COMPARE REG1, REG2 101: JUMP_IF_EQUAL CURRENT+10 … … Read more
With CMake, it’s generally recommended to do an “out of source” build. Create your CMakeLists.txt in the root of your project. Then from the root of your project: mkdir Release cd Release cmake -DCMAKE_BUILD_TYPE=Release .. make And for Debug (again from the root of your project): mkdir Debug cd Debug cmake -DCMAKE_BUILD_TYPE=Debug .. make Release … Read more
The size_t type is the unsigned integer type that is the result of the sizeof operator (and the offsetof operator), so it is guaranteed to be big enough to contain the size of the biggest object your system can handle (e.g., a static array of 8Gb). The size_t type may be bigger than, equal to, … Read more
Basically copying and pasting from Bjarne Stroustrup’s “The C++ Programming Language 4th Edition”: List initialization does not allow narrowing (§iso.8.5.4). That is: An integer cannot be converted to another integer that cannot hold its value. For example, char to int is allowed, but not int to char. A floating-point value cannot be converted to another … Read more