Comparing characters.

This is a discussion on Comparing characters. within the C++ Programming forums, part of the General Programming Boards category; I'm trying to get a program to run where I need to take in input and show whether it's part ...

  1. #1
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    Comparing characters.

    I'm trying to get a program to run where I need to take in input and show whether it's part of the alphabet or not (a - z, A-Z ). When I try to put in a command like this..

    char a;
    if (a >= "a" || a <= "z")

    , it gives me a bunch or errors. What do I need to do to get it to recognize letters in the alphabet?

    Thanks in advance.

  2. #2
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    well...start with single quotes instead of double. ", '

  3. #3
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    Ah, that made it so I can compile. But it's still reading in semicolons and printing them out though I said for it to read from 'a' to 'Z'.

  4. #4
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    Aug 2001
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    61
    Change

    if (a >= 'a' || a <= 'z')

    to

    if (a >= 'a' && a <= 'z')

  5. #5
    Registered User
    Join Date
    Nov 2001
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    30
    To include capitals as well...

    if ((a >= 'a' && a <= 'z')||(a >= 'A' && a <= 'Z'))

    Homer

    D'OH!

    mmmmmmmm... iterations

  6. #6
    Super Moderator VirtualAce's Avatar
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    char Alphabet []={A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X, Y,Z,
    a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y, z};

    char TestCharacter='A';

    char *ptr=strchr(Alphabet,TestCharacter);

    if (ptr)
    {
    //Character is valid
    }
    else
    {
    //Character is invalid
    }


    You can also check the ASCII value of the input character. If it is in range (65-90 for capitals and 97-122 for lower case) then it is
    part of the alphabet.


    int hit=kbhit();
    int ch=0;

    if (hit)
    {
    ch=getch();
    }

    if (ch>=65 && ch<=90 || ch>=97 && ch<=122)
    {
    //Character is in the alphabet
    }

    kbhit() would be in a loop constantly checking to see if a key had been hit. If you do not wish to check for both ranges, simply convert the character to upper case or lower case with strlwr() or strupr() and compare to the upper or lower case ASCII codes respectively. This is the same as if (ch>'A'....) since 'A' represents the number 65.

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