The error is generated by the linker because it can not see where the definition of the constructor is located. If you are using an IDE, you should add both .cpp files to the project so that they can be compiled together and the definition would be found by the linker. It not, then you … Read more
Your hi method is not declared as const inside your A class. Hence, the compiler cannot guarantee that calling a.hi() will not change your constant reference to a, thus it raises an error. You can read more about constant member functions here and correct usage of the const keyword here.
The most efficient way would be just to iterate over the string until you find a non-digit character. If there are any non-digit characters, you can consider the string not a number. Or if you want to do it the C++11 way: As pointed out in the comments below, this only works for positive integers. … Read more
The error message clearly says that the default constructor has been deleted implicitly. It even says why: the class contains a non-static, const variable, which would not be initialized by the default ctor. Since X::x is const, it must be initialized — but a default ctor wouldn’t normally initialize it (because it’s a POD type). Therefore, to get a … Read more
For future people struggling with a similar problem, the situation is that the compiler simply cannot find the type you are using (even if your Intelisense can find it). This can be caused in many ways: You forgot to #include the header that defines it. Your inclusion guards (#ifndef BLAH_H) are defective (your #ifndef BLAH_H doesn’t match your #define BALH_H due … Read more
The best thing to do is to use the algorithm remove_if and isspace: Now the algorithm itself can’t change the container(only modify the values), so it actually shuffles the values around and returns a pointer to where the end now should be. So we have to call string::erase to actually modify the length of the container: We … Read more
It has uses in both C and C++. As you guessed, the static part limits its scope to that compilation unit. It also provides for static initialization. const just tells the compiler to not let anybody modify it. This variable is either put in the data or bss segment depending on the architecture, and might be in memory marked read-only. … Read more
so your answer is But naturally, this is a bad practice, just use typedefs 🙂 Extra: Wonder how to declare an array of 3 pointers to functions taking int and returning a pointer to an array of 4 pointers to functions taking double and returning char? (how cool is that, huh? :)) :))
It is possible to turn the string into a stream by using the std::stringstream class (its constructor takes a string as parameter). Once it’s built, you can use the >> operator on it (like on regular file based streams), which will extract, or tokenize word from it:
There are several ways, but first you need to understand why object cleanup is important, and hence the reason std::exit is marginalized among C++ programmers. RAII and Stack Unwinding C++ makes use of a idiom called RAII, which in simple terms means objects should perform initialization in the constructor and cleanup in the destructor. For instance the std::ofstream class [may] … Read more