[Gambas-user] C Code character manipulation - alternatives

[Doriano Blengino]

KhurramM ha scritto:
> Thanks Sir.
>
> You have given me tips better then the book I am following on C. :working:
>
> My two queries:
> 1> Can I implement ctrl+D or ^D, which I am not able to here, as in C?
> 2> The program works with INPUT and LINE INPUT. But Line Input also takes
> blank space as input, while INPUT ends the program over here. And I use
> string here, but in C it was integer?
>
> --------------------------------------------------- Just for reference:
> Well I made my program final as:
>
> PUBLIC SUB Main()
>
>    ' Declare AND initialize variables.
>    DIM c, count AS Integer
>    
>    DIM c1 AS String
>  
>    ' READ , PRINT , AND count characters.
>    PRINT "Enter characters (or Press Carriage Return to quit): "
>    LINE INPUT c1
>    count += Len(c1)
>
>    WHILE (c1 <> "")    ' This is the best solution
>       PRINT c1
>       LINE INPUT c1
>       count += Len(c1)
>    WEND 
>
>    ' PRINT the number OF characters printed.
>    PRINT count & " characters printed."
>    
> END
>   
I put the following code in a program; the code is invoked by pressing 
Button1:

    PUBLIC SUB Button1_Click()
       ' Declare AND initialize variables.
       DIM c, count AS Integer
      
       DIM c1 AS String
     
       ' READ , PRINT , AND count characters.
       PRINT "Enter characters (or Press Carriage Return to quit): "

       WHILE NOT Eof
          LINE INPUT c1
          PRINT c1
          count += Len(c1)
       WEND

       ' PRINT the number OF characters printed.
       PRINT count & " characters printed."
    END

Running the program inside the IDE, and using the internal console, no 
EOF is generated, but your version (which tested for empty lines) 
worked. Then I made an executable (Project menu -> Generate -> 
Executable) and launched it from a terminal. It runs correctly; you 
repeatedly type some text + ENTER, or you type Ctrl-D. The behaviour is 
correct and, as I was supposing, no Ctrl-D is detected inside the line 
input, but it is if you type ^D alone. As the routine is invoked every 
time Button1 is pressed, I tried to press Button1 again: after the first 
^D no more characters are detected. This makes sense, because you cannot 
go past the EOF...
Then I launched the following shell command: echo "ciao" |./dand.gambas
Doing so, the standard input for the program is redirected elsewhere 
(the output of the echo command). The program works as expected - it 
counts 4 characters and senses the EOF correctly.

Now, I suppose you are disappointed by INPUT and LINE INPUT, which are 
multi-char statements. If you want to process single characters, then 
you must use the READ statement (perhaps there is also a INKEY$) -- see 
the docs. Anyway, gambas does not have chars like C - you can use 
strings (of length 1); the ASC() function returns the numerical code of 
a character, and CHR() returns a char (a string of len 1)  by giving its 
ascii code. There is no character to designate EOF - you must use the 
Eof() function.

If you want to be a real gambas programmer, stop to put parenthesis 
around tests, like "while (c1<>...)"! :-)

If you have a goal in mind, perhaps could be better you tell it, so we 
can help you more precisely.

Cheers,

-- 
Doriano Blengino

"Listen twice before you speak.
This is why we have two ears, but only one mouth."