std

Given the following code: /*Formatting Output **Goal: practice using cout to format output to console **Print the variables in three columns: **Ints, Floats, Doubles */ #include <iostream> #include <iomanip> using namespace std; int main() { int a = 45; float b = 45.323; double c = 45.5468; int aa = a + 9; float bb = b + 9; double cc = c + 9; int aaa = aa + 9; float bbb = bb + 9; double ccc = cc + 9; // 1st attempt :> cout << "\n\n\n" << "// 1st attempt :>" << "\n"; cout << "12345678901234567890123456789012345678901234567890" << "\n"; cout << "Ints" << setw(15) << "Floats" << setw(15) <<

std::string.c_str() returns a (const char *) value. I Googled and found that I can do the following: std::string myString = "Hello World"; char *buf = &myString[0]; How is this possible? &myString[0] is an object of type std::string , so how can this work? &myString[0] is a object of type std::string No it isn't. myString[0] is a reference to the first character of the string; &myString[0] is a pointer to that character. The operator precedence is such that it means &(myString[0]) and not (&mystring)[0] . Beware that, accessed this way, there's no guarantee that the string will be zero

I've found that function default_error_condition doesn't work as expected in my code auto ec = std::system_category().default_error_condition(EACCES); std::cout << ec.value() << std::endl << ec.category().name() << std::endl; Returned ec value has system error category, but it has to be generic , if I got it right from the documentation e.g. cppreference and gcc source code system_error.cc UPD: also found this remark in the standard 19.5.1.5 Error category objects The object’s default_error_condition virtual function shall behave as follows: If the argument ev corresponds to a POSIX errno

I am trying to "hack" a game (Red Alert 3), I try to make a program which shows the unit list of my opponents. As for that I first need to find a (static) pointer to my own list which I can do on single player. I have noticed this behaviour: (by looking at which addresses are changed by the add_unit code): if a units hasn't been build yet, create a new address for it (random?) and set the value to 1 (amount of units of that type) when the unit has been already build once in the game, increment the original address of the unit type by 1 This looks to me like std::vector behaviour. Now I am

I had always thought that the standard required the non-specialized template for std::equal_to<T> to call T::operator== , but I noticed the description at cppreference.com almost implies it's the other way around; certainly it doesn't mention it as a requirement. I also checked the C++11 draft standard N3337 and couldn't find any guarantees there either. If you create a class with an operator== you'd hope it would get used in all circumstances. I can't honestly think of a way to implement std::equal_to that wouldn't work this way, but am I missing something? Is std::equal_to guaranteed to call

What's the fastest way to "clear" a large STL container? In my application, I need to deal with large size std::map , e.g., 10000 elements. I have tested the following 3 methods to clear a std::map . Create a new container every time I need it. Calling map::clear() method. Calling map::swap() method. It seems that ::swap() gives the best result. Can anyone explain why this is the case, please? Is it safe to say that using map::swap() method is the proper way to "clear" a std::map? Is it the same for other STL containers, e.g., set , vector , list , etc. m_timer_start = boost::posix_time: