C++ strong types

[frek]

Hi all,

I encountered such a term "C++ strong type" and have no clue what it is. I also surfed the Web but the resources explaining it are either too advanced or too detailed.

Will you say what a cpp strong type is, in simple language, and demonstrate it with an example, please?

I've heard that it's very important in embedded programming.

[Zaap]

I guess this is about strongly-typed/strong typing.

This basically means variables know their type at compile time and it wont change.

For example, you're not obliged to strong type with python, so you can write

def fun(a, b):
    return a + b

And you can give whatever you want to this function, but in C++, you have to do one function per type or to template it (which is going to create at compile time a version of the function for each type used with it in your code).

[Ganado]

There's two dimensions when it comes to typing in a language.
- First one is the weak vs. strong dimension.
- Second one is the static vs. dynamic dimension.

Weak vs. strong, in my understanding, is how specific a type needs to be, and how easily it can be implicitly converted or used as another type. For example, a string is different than an int. If you have a function that takes in a string, you can't pass it an int. On the other hand, a double also is not an int, but if you pass an int into a function expecting a double, it will be implicitly converted into a double, so this is "weaker" in a sense. A void* (void pointer) is about the weakest type in C++, because it can point to basically any other type of object.

error: could not convert 'a' from 'int' to 'std::string {aka std::basic_string<char>}'

Static vs. dynamic is about whether or not types are known at compile-time.

C++ is a static language, because all objects have a particular type at compile-time. You can't change the same object from a Foo to a Bar at run-time. However, parts of C++ have weak typing, because when you see an object of type void*, you don't actually know what the object it points to is.