I'm starting a project using C++, which I haven't used before outside of a handful of school projects - nowhere near the scope of what I'm tackling now.
My goal is to try my best to follow the C++ Core Guidelines as I work to avoid errors, improve performance, and most importantly: improve maintainability of my code.
I've been running into literally hundreds of issues ranging from my g++ / Clang++ versions not being right to standard libraries not being found to g++ using the wrong version of C++ for compilation to very basic functions not behaving as expected - and I haven't even started to look into autotools, so I expect many more headaches to follow.
This question is specific to one part of the C++ Core Guidelines, though. Interfaces 6: Prefer Expects() for expressing preconditions
I tried writing the following simple code:
#include <iostream>
using namespace std;
int square(int x) {
Expects(x > 0);
return x * x;
}
int main() {
cout << square(3) << endl;
return 0;
}
This threw an error in g++:
$> g++ -std=c++17 main.cpp
main.cpp: In function ‘int square(int)’:
main.cpp:7:2: error: ‘Expects’ was not declared in this scope
Expects(x > 0);
^~~~~~~
-> [1]
I tried using Clang, as well, but it has an entirely different (and unrelated) problem:
$> clang++ -x c++ main.cpp
main.cpp:1:10: fatal error: 'iostream' file not found
#include <iostream>
^~~~~~~~~~
1 error generated.
-> [1]
I haven't figured out how to fix that one yet, so I'm not bothering with it.
sudo apt-get installsomething to get the GSL stuff? – Sperling