A few quick questions

This is a discussion on A few quick questions within the C Programming forums, part of the General Programming Boards category; Hi all, I'm new to C, and I'm just beginning to experiment. What I want to do it take an ...

  1. #1
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    A few quick questions

    Hi all, I'm new to C, and I'm just beginning to experiment.

    What I want to do it take an input, write it to an array, then print only the lowercase letters or the capital letters.

    Also, with the same array, is it possible to print only the Nth letter?

    Thanks in advance,
    Brodie.

  2. #2
    Kernel hacker
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    Yes, writing the nth letter of a string (character array) is done by displaying str[n-1] (0 being the first letter, so nth letter is n-1).

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  3. #3
    apprentiCe
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    Ascii Table - ASCII character codes and html, octal, hex and decimal chart conversion

    you can check each character if it belongs to uppercase range or lowercase range and branch accordingly

    that means,
    if you want to see if letter is uppercase or not
    Code:
    if(ch>=65 && ch<=90)
    {
       //its upper case
    }
    another method is to use isupper() or islower() functions in ctype.h library

    <ctype.h>

    to print only nth letter you have to print element having its index as (n-1)
    Last edited by creeping death; 03-30-2009 at 03:24 AM.
    Code:
    printf("%c%c%c%c%c%c%c",0x68,0x68^0xd,0x68|0x4,0x68|0x4,0x68|0xf,0x68^0x49,0x68^0x62);

  4. #4
    CSharpener vart's Avatar
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    Quote Originally Posted by creeping death View Post
    another method is to use isupper() or islower() functions
    it is preffered method as it will work for any encoding even that has no sequential coding for characters

    also - do not use magic numbers
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  5. #5
    apprentiCe
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    Quote Originally Posted by vart View Post
    it is preffered method as it will work for any encoding even that has no sequential coding for characters

    also - do not use magic numbers

    yes, you should define the range as something like

    Code:
    #define UPPER_START 65
    #define UPPER_END 90
    and then use UPPER_START and UPPER_END in place of actual numbers...

    my bad.
    Code:
    printf("%c%c%c%c%c%c%c",0x68,0x68^0xd,0x68|0x4,0x68|0x4,0x68|0xf,0x68^0x49,0x68^0x62);

  6. #6
    CSharpener vart's Avatar
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    just 'A' and 'Z' would do...
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    I'd suggest using the characters if you are going to do your own comparison:
    Code:
    if(ch>='A' && ch<='Z')
    {
       //its upper case
    }
    That way, we don't have to look it up in the ASCII table to figure out what it is. And it has a remote chance of working even if the character encoding is NOT ASCII (although it presumes that all letters in the alphabet are in order [which it is in ASCII, and ALMOST in EBCDIC but there are gaps in EBCDIC].

    --
    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.

  8. #8
    Woof, woof! zacs7's Avatar
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    Or just use isalpha() from ctype.h that way it doesn't matter at all

  9. #9
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    Quote Originally Posted by zacs7 View Post
    Or just use isalpha() from ctype.h that way it doesn't matter at all
    islower or isupper if you want to check if it's lower/upper case - yes, that'll work for BOTH ASCII and EBCDIC along with any other character encoding where the compiler/library supports standard C functions.

    --
    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.

  10. #10
    and the Hat of Guessing tabstop's Avatar
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    Quote Originally Posted by creeping death View Post
    yes, you should define the range as something like

    Code:
    #define UPPER_START 65
    #define UPPER_END 90
    and then use UPPER_START and UPPER_END in place of actual numbers...

    my bad.
    I think this is following the letter of the rule and not the spirit, since 65 and 90 are still magic numbers; and 'A' and 'Z' are still more readable (in context, UPPER_START makes sense, but looking at this define line without seeing it used, I'm not sure I would recognize the numbers).

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    Hey.. thanks alot.. but as I'm very new, I'm having trouble adding a string of variable length to said array...


    The idea is to be able so print, say the capitals, the lowercase and the integers in a given string, all of different lines

    Thanks,
    Brodie.
    Last edited by Brodie337; 04-06-2009 at 12:58 AM.

  12. #12
    CSharpener vart's Avatar
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    Quote Originally Posted by Brodie337 View Post
    Hey.. thanks alot.. but as I'm very new, I'm having trouble adding a string of variable length to said array...


    The idea is to be able so print, say the capitals, the lowercase and the integers in a given string...

    Thanks,
    Brodie.
    string basically is an array of chars - so you can assign it char by char... just add the nul-character at the end.

    if you need the more complex formating - read about sprintf
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    Allright... I can get a string of characters into an array... Now I need to get the capitals out of said array...
    What I'm using looks like this:
    Code:
        while (isupper (msg))
            putchar(out[j++]);
    But I get the error message when colpiling:
    Code:
    In function `int main()':|
    error: invalid conversion from `char*' to `int'|
    error:   initializing argument 1 of `int isupper(int)'|
    Can someone shed some light on this?
    Last edited by Brodie337; 04-06-2009 at 07:31 PM.

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