Strong Typing?

[bcholmes]

Geek question:

What is the feature of a language that you consider "strong typing"? How does strong typing manifest itself (or not) in your favourite language or two?

Comments

[erik]

(and in fact the last time I was using BASIC (which admittedly was Cro Magnon BASIC on I believe a Commodore PET), it would do what I think. I did it all the time, that's where I came up with the example. (if foo<128, foo=foo+128, endif. Ta da! Force caps!))

[erik]

(sorry, make that -64, not +128. Been too long.)

[king-tirian.livejournal.com]

Huh, every flavor of BASIC I ever used (including but not limited to QBASIC, QuickBASIC, and Visual Basic for DOS) was different and very strongly typed. "a"+1 would generate a syntax error. If you wanted to turn "a" into "b", you'd need to do CHR$(ASC(foo$)+1)), and if you wanted to turn "a" into "a1", you'd need to do foo$ + STR$(1).

[erik]

interesting.
Either I'm misremembering the multiple layers of casting as in your example (it was 25 years ago, after all) or maybe I was doing peek-poke things to get around it...or Commodore BASIC was different.
All are equally likely.

I know that TUTOR (the language I worked in professionally in the 80s) and original K&R C both do it my way. C especially I remember transitioning from K&R to ANSI C and running up against the typing restrictions.

[http://users.livejournal.com/merle_/]

You're probably just channelling old C memories, not BASIC.

char a = 'a';
a = a + 1;
/* a == 'b' now */

If your character is represented as a char/byte, then yes, incrementing it shifts the letter up. But if it's a string then it depends on how "+" is interpreted: either it will concatenate a "1", or, horrors, it will increment your pointer and...

Some BASICs let you work with character codes. Commodore BASIC had tons of poke/peek/call things that were basically invoking magic machine code, so you would probably have been passing char/byte values around.