C++17 in Detail: A Deep Dive/

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Third standard attribute

Third standard attribute

This section delves into the details of the third standard attribute called nodiscard.

We'll cover the following...

The third standard attribute we get in C++17 is:

[[nodiscard]] attribute

[[nodiscard]] can be applied on a function or a type declaration to mark the importance of the returned value:

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#include <iostream>
using namespace std;
[[nodiscard]] int Compute();
void Test() 
{
  Compute(); // Warning! return value of a
          // nodiscard function is discarded
}

The above code should emit a warning when you compile it as you haven’t assigned the result to a variable.

What it means is that you can force users to handle errors. For example, what happens if you forget about using the return value from new or ...