Possible Duplicates:
What is a strictly typed language?
What are the key aspects of a strongly typed language?
What does it mean that language is strongly typed?
views:
163answers:
6
A:
Look at http://eli.thegreenplace.net/2006/11/25/a-taxonomy-of-typing-systems/ and http://en.wikipedia.org/wiki/Type_system
Patrick
2010-06-01 12:06:54
+3
A:
"Strong typing" can have slightly different meanings depending on context (or who you ask), but generally it means that a language will not implicitly convert one datatype to another.
mipadi
2010-06-01 12:07:25
+1
A:
The terminology around typing is dreadfully confusing. One interpretation is that of type safety - whether a language allows you to subvert the type system.
C and Delphi do, by having void * and Pointer types, respectively.
Java and C# does not: even though there's Object, you will get a runtime exception if you try casting a Foo to Object only to cast it into Bar (where Bar and Foo are not in the same inheritance chain).
Note that "strongly typed" is independent of manifest typing - declaring the types of your variables like C or Java - and latent typing, where you don't, like Smalltalk.
Frank Shearar
2010-06-01 12:12:04
+1
A:
Back in the day we didn't have these namby-pamby "dynamic" languages - men were men, boys were boys and ints were ints. A char by any other name was just a byte. We had to cast our variables explicitly both ways through an assignment operation. You kids today have it easy, doing arithmetic operations on strings and concating variables with a compiler error in the world! And you're all into this duck-type thing with weak values...
Seriously though, strong typing means that the language places restrictions on your data types. You have to explicitly give your variables a type (such as int or string) and you need to cast or convert them when you want to change them to another type. C++ and Java are examples of strongly typed languages. In those languages you can't do:
"12" / 3;
Since you can't divide a string by an integer. However some languages such as perl and python will let you do that, and "12" will be converted to 12 automagically.
Niki Yoshiuchi
2010-06-01 12:22:49
Explicitly declaring types is a different trait, actually. Type inference can be had in strongly-typed languages too. See C# and F# for example.
Joey
2010-06-01 12:25:25
There are also dynamic languages that are somewhat strongly typed such as Python, where data types can't change once a variable is declared. Javascript is truly weakly typed, as the datatype of a variable can change on the fly.
Keith Rousseau
2010-06-01 12:27:29
Yeah, I'm familiar with type inference as my favorite language is OCaml. However you are still giving your variables types, you just aren't naming them. Also I wanted to simplify my answer. I did not realize that Python was strongly typed. Thanks for letting me know!
Niki Yoshiuchi
2010-06-01 13:08:16
When exactly *was* "back in the day"? Lisp (the very first dynamically typed programming language) was created in 1958, only a few months after Fortran (the very first statically typed programming language). So, the only time when "we didn't have these namby-pamby dynamic languages" but only static languages was a brief period in the winter of 1957/58. (And if I remember correctly, 1958 was the first *implementation* of Lisp, the first *specification* was in 1954, if I'm not mistaken.)
Jörg W Mittag
2010-06-01 13:20:59
Dynamic typing is actually the opposite of static typing, both of which are orthogonal to strong vs. weak typing.
mipadi
2010-06-01 13:54:44