While playing around with C++, I discovered that the following code enum E* kind; int main() { } compiles on MSVC v19.latest. I expected this to fail, as E is not declared yet. GCC and Clang give appropriate error messages error: use of enum ‘E’ without previous declaration and error: ISO C++ forbids forward references… Read More MSVC: Why does use of enum without prior declaration compile?

I would like to create a const std::vector to contain all the elements of two other const std::vector of the same type. #include <iostream> #include <vector> int main() { const std::vector<int> int_a{0,1}; const std::vector<int> int_b{2,3}; const std::vector<int> all_ints; for (int i: all_ints) std::cout << i << ‘ ‘; return 0; } For the example above… Read More Create const std::vector as the concatenation of two const std::vector

I am building a C test program on Linux. Why does this code compilation fail below? After list_t is type-defined, shouldn’t the compiler understand later that it is the same type as a struct list ? The attempt to create a new list item using malloc() fails with error: invalid type argument #include <stdio.h> #include… Read More C struct pointer types are the same but still fails

I am trying to declare multiple int with the help of for loops in c. The code almost looks like for (int x = 0; x < 45; x++){ int valx = 10*x; } The goal is to have a variable called val0 = 0, val1 = 10, val2 = 20…… I also need to… Read More Declaring multiple int with for loops in C

I want to write a variable that takes a list of functions, is that even possible? to have a list of functions in C? example: // this type is for one function void (*f)(void) = func1; // but this is what I need /*TYPE*/ vf = { func1, func2, NULL }; I dont want to… Read More c, list of functions; type

I’m a complete newbie to C++ so bear with me. I am defining a class called ‘logging’ which is currently write in main.cpp. Now that I am trying to split implementation (log.cpp) from declaration (log.h), I have the following situation that bring me to compiler error ‘identifier logging is undefined’: log.cpp #include <iostream> #include <unordered_map>… Read More Declare C++ Class (identifier logging is undefined)

I have the following statement: if(Estatu== "INF"){ MIN <- 5 } else if (length(Estatu)==0) { MIN <- 0 } It’s very simple, but Estatu sometimes has INF and other times it’s an empty value (character 0). I have two problems: When the value is character(0), it indicates the following error: Error in if (Estatu== "INF")… Read More Declaration with argument length zero in R

I’ve already read this, this and this but it seems they’re not exactly my situtation. I have a code like this struct ppl_weight { uint16_t weight; uint8_t weightHour; } ppl_weightList[16]; but I can’t understand the array at the end of the struct. What does it mean? Have I an array of 16 struct? How does… Read More What does the variable array name at the end of the structure's definition means?