Typecasting questions...
Firstly, i made the following program that's supposed to convert an int to a char and back to an int. Why does it output a negative number?
And secondly, why is it, on windows XP (not sure about vista) that the following program forces the computer to make a beeping sound?Code:#include <iostream> using namespace std; int main() { cout<<(int)((char)177); cin.get(); }
ThanksCode:#include <iostream> using namespace std; int main() { cout<<(char)7; cin.get(); }
1) For your compiler, char is apparently signed, 177 overflows, wraps around and becomes negative. Try unsigned char instead.
2) ASCII characters with small values are "non-printing" characters, they were meant to represent actions, rather than character symbols. Char 7 happens to represent "Bell".
Ascii table
I might be wrong.
Quoted more than 1000 times (I hope).Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
Thanks... but what exactly is "Bell"?
ASCII code 7, known as "BEL", is used by standard (aka console mode) applications to make a sound on the inbuilt speaker of the computer. It is normally used by programs to sound an audible beep.
It's the character that on a Teletype [typewriter style "terminal"] would ring a mechanical bell [like the end-of-line bell on a classic typewriter].Originally Posted by yaya
You can actually make that sound "portable" by using the char '\a' (just like newline is '\n'). [I'm not sure there are any systems that actually DON'T use 7 as a BEL character, but there may be - I expect non-ASCII-based character sets, such as EBCDIC could do that].
--
mats
Compilers can produce warnings - make the compiler programmers happy: Use them!
Please don't PM me for help - and no, I don't do help over instant messengers.
Thanks everyone... I understand now
On a side note, when using C++, you are advised to use C++ type-casting. They include dynamic_cast, static_cast, reinterpret_cast and const_cast (to my knowledge; not sure if there are more).
You could read up a little about them or someone could explain it, I guess.
Well, yeah. But rewriting the code in the original post to use C++-style casts has no effect on the question asked.
Indeed, thus the side note
