What is dynamic programming language?

Answer 1

Dynamic programming languages are often refered to as 'weakly typed' which means that variables are not bound to a particular type until runtime. For example, C++ is a 'strongly typed language, while Perl is a 'weakly typed' or 'dynamic' language.

A strongly typed language requires that you specify a type:

int i = 0;

In that C++ snippet, an integer names i is created and assigned the value of 0. The following would not compile in C++:

int i = 0;

i = "Hello world";

This would fail because i has been declared to be an integer and can not be assigned a string value. The following code would succeed in a dynamic language like Perl:

i = 0;

i = "Hello world";

The type is not declared here at all, because it is not bound to a type until runtime. In the first statement, i is bound to an integer type but in the second statement it is bound to a string type.

While dynamic language are easier to program in, they are much slower than strongly typed languages and are generally regarded as less safe since checking is not done until run time.

Answer 2

A dynamic language is a language that displays text in a dynamic, non-static, manner, without having to change the source of a file; dynamic languages can also perform a number of tasks, such as information retrievement and insertion. Dynamic languages are primarily used for modern computer applications. For example, a dynamic language may be used to output the name of a user, in which was entered through an HTML input element, and processed by the dynamic language to actually log the user in. A static language cannot do this.

Answer 3

Dynamic programming languages do not strongly type the variable types at compile time, but infer the type of variables at run time. These languages also typically have inferencing based upon use. For example:
var myValue = "123";
print myValue;
myValue = myValue + "456"; //Concats a string
print myValue;
myValue = myValue + 456; //Infers the value as a number, and adds to the value
print myValue;
Results:
123
123456
123912