sharadpro

What is the difference between C++'s Standard Library and Standard Template Library?

andro

The Standard Template Library makes up a large part of the Standard Library.

sarumont

The biggest difference is that the STL uses templates (hence the T) to provide some more advanced data structures. These data structures are type-agnostic, a benefit derived from templates.

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grumpy

That's has an element of truth, but is not really that true. The use of templates in the STL makes the containers, algorithms, etc applicable to a wide range of data types. The sorts of data structures used in the STL are, at heart, no different from data structures supported by most modern programming language.

And there is much more to the STL than data structures.
The STL is not type agnostic; it is better described as type generic. It is designed so it works with a wide range of types. But those types have to obey certain rules.

For example, there are various conditions that a type, X, must satisfy before a std::vector<X> can be declared and used. One of those conditions is that X must be copyable (eg it is a basic type, or a class with a valid copy constructor and assignment operator). Similarly, there are certain conditions that must be met for algorithms in the STL to work. For example, the std::sort() algorithm requires that the type it works with can be compared by value (to determine if x1 < x2 or not).

sarumont

I should have added "and many related algorithms" to that. A container is, in fact, a data structure itself.

Iterators are also a big addition in the STL that I neglected to mention. My main point, though, was that most everything in the STL is generic. The provided algorithms and features (such as iterators) tend to lend themselves to the containers provided (as well as those you can build yourself using templates).

Yes, generic is the better term. I was thinking more toward C++-provided types, but user-defined types must definitely be obedient to the rules that you have provided (and possibly more), depending on what algorithms you use from the STL.

Once again, the biggest point of difference here is the generic nature of the STL-provided algorithms, data structures and constructs.

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"Time is an illusion. Lunchtime doubly so."
-the late, great Douglas Adams