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As other people have said, you need to implement a comparison function yourself.

There is a proposed way to ask the compiler to generate the obvious/naive(?) implementation: see here.

It may seem a bit unhelpful of C++ not to have already Standardised this, but often structs/classes have some data members to exclude from comparison (e.g. counters, cached results, container capacity, last operation success/error code, cursors), as well as decisions to make about myriad things including but not limited to:

C++20 introduced default comparisons, aka the "spaceship" operator<=>, which allows you to request compiler-generated </<=/==/!=/>=/ and/or > operators with the obvious/naive(?) implementation...

auto operator<=>(const MyClass&) const = default;

...but you can customise that for more complicated situations (discussed below). See here for the language proposal, which contains justifications and discussion. This answer remains relevant for C++17 and earlier, and for insight in to when you should customise the implementation of operator<=>....

It may seem a bit unhelpful of C++ not to have already Standardised this earlier, but often structs/classes have some data members to exclude from comparison (e.g. counters, cached results, container capacity, last operation success/error code, cursors), as well as decisions to make about myriad things including but not limited to:

It's easy to leverage std::tuple's comparison operators to compare your own class instances - just use std::tie to create tuples of references to fields in the desired order of comparison. Generalising my example from here:

It's easy to leverage std::tuple's comparison operators to compare your own class instances - just use std::tie to create tuples of references to fields in the desired order of comparison. Generalising my example from here:

A consistent approach to ==, etc

A consistent approach to ==, <, > <= etc