Type Implementations¶

Dynamically Typed Languages¶

Whether implicitly or explicitly, all values in a program have a data type.

Dynamically typed languages do not require that the data type be declared, and type checking occurs at runtime. These languages typically infer the type of a variable based on the value assigned to it. For example, the following JavaScript code assigns a string to the firstName variable and a numeric value to the age variable, then prints the type of each variable:

const firstName = "Arie";
const age = 21;
console.log(typeof firstName);
console.log(typeof age);

Statically Typed Languages¶

Statically typed languages require that variables be declared with a specific type before they can be used.

string firstName = "Arie";
int age = 21;

Because the data type is known at compile time, the compiler can provide type safety, and prevent code from being compiled if there is a type mismatch. If a function expects a string, and you pass it an integer, the compiler will not allow it to compile.

Custom Types¶

The type system not only descibes primitive types like integers and strings, but provides the means to create custom types. Classes are the primary way to create these custom types in C#. Other options include records, structs, and enumerations.

Additional Resources¶

We will cover the what is needed to follow the concepts in this book. If you would like to learn more about data types that C# supports see the following documentation:

If you are new to object oriented programming you may also follow these tutorials: