禁用 C++ 中的检查语句

Question

Say that my main code calls functions like myarray(i) where the length of myarray is N . During the development I would probably want to have a CheckIndex function inside the () overload. However, this turns out to waste computation time when the number of iterations is large. Another example would be to check if there is consistency in the dimensions of two matrices before adding them, or checking if the denominator in this expression my_2D_array_instance/value where value is a double , is not too small or zero.

My question is if there is a way to give the option to the user to tell the compiler "skip those checks" and if yes, how to do it?

Answer 1

As πάντα ῥεῖ stated in the comment section you can use preprocessor conditionals to avoid compiling code you don't want to be part of the compilation, take the code:

    std::array<int, 5> a{1, 2, 3, 4, 5};

#ifdef DEBUG
    std::cout << a.at(5); //out of range
#endif

    std::cout << a.at(3);

With a normal compiler instruction the code inside #ifdef will not be compiled, but if you define DEBUG (you can name it whatever you want), when you compile it, ie :

g++ main.cpp -Wall -Wextra -pedantic -D DEBUG 
                                     ^^^^^^^^

All the code will be compiled.