Android Question Char = Int?

[wonder]

Why isn't it possible to perform arithmetic with chars and ints, without having to use the asc() function?

'Not legal
Dim d = "d" As Char
Dim a = d - 3 As Int

'Legal
Dim d = "d" As Char
Dim a = asc(d) - 3 As Int

Isn't char a primitive type?

 

[DonManfred]

Isn't char a primitive type?

Primitives include the numeric types: Byte, Short, Int, Long, Float and Double.
Primitives also include: Boolean and Char.

 

[wonder]

So... isn't Char just an Int "disguised" as an ASCII character?
Shouldn't we be able to add and subtract without using the asc() function?

 

[DonManfred]

The problem seems that "d" (the Char object) cannot be cast to a number...

Char "d" will result in "d", not in a number... To get the int you need to use asc("d")

isn't Char just an Int "disguised" as an ASCII character?

the value of char does not fit into 0-255 like you expect i guess. char can hold a value of 0 to 65535

 

[sorex]

because a char is a "presentation" and not a value

 

[sorex]

also in some languages A+1 will return A1 and not B

 

[wonder]

char can hold a value of 0 to 65535

So the B4A char is nothing like the C-family char... right?

(Sorry for nagging about this, I'm timing some code to the nanosecond...)

 

[Cableguy]

I remember back I the early z80 qbasic, I used to create menu borders by using the Char$ keyword to access "symbols" not directly available with the keyboard

At that time we didn't have that much fonts, so it was like looking up a fixed table, now, with all the existing fonts, char(250) can be a letter or a symbol depending on the font in use

 

[sorex]

char used to be 0-FF but due to unicode etc it's expanded to 16 bit.

 

[DonManfred]

So the B4A char is nothing like the C-family char... right?

cant answer this. NEVER used C and i dont know the rules of C objects...

 

[wonder]

char used to be 0-FF but due to unicode etc it's expanded to 16 bit

This cleared all my doubts, @sorex.

 

[wonder]

Here's a surprising result... My function is more than 10x faster...

 

[sorex]

compared to what? parseInt?

 

[wonder]

Compared to B4A direct assignment using parseDouble.
Generated Java code:

 //BA.debugLineNum = 22;BA.debugLine="i = s";
_i = (int)(Double.parseDouble(_s));

 

[sorex]

what do you get with the parseInt method? that should be faster.

 

[wonder]

I win.

 

[sorex]

strange, here it's the opposite and your is 8-10 times slower

 

[wonder]

B4J as well? x86 or x64 Windows?
Here: Windows 8.1 64-bit

 

[sorex]

no, under android this is a B4A thread

more weirdness...

I copied the sub and named it getInt2

when I call that it's a lot faster than the original sub, even when swapping the calls. wth!

 

[sorex]

in release mode is always seems to win compared to parseInt, logical as that supports more than 10 base alone.

it's still creepy that the differences between calling the same routine can be so huge.
(I'm talking here abte the time of 10.000 runs of the same sub call)