Thread: telling if a value is alphabetic or numaric?

  1. #1
    Geo Geo Geo-Fry
    Join Date
    Feb 2003

    telling if a value is alphabetic or numaric?

    is there a way to check if an inputed value is a letter or number? because i have this program that needs a user to type in a bunch of numbers (0-9) and if you put in a number ever, it automaticly fills everyone with a zero. i tried this:
    if(x != 1 && x != 2 && x != 3.... && x != 9)
      cout <<"That's not a valid number";
      b--;       //b is used to count how many ints the have put in, dont want it to think that it was a valid value
    but it didnt work.
    thanks in advance for any help!
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  2. #2
    Registered User
    Join Date
    Nov 2002
    cctype or ctype.h depending on compiler.

    look up isdigit() and isalpha()

  3. #3
    Skunkmeister Stoned_Coder's Avatar
    Join Date
    Aug 2001
    If this isnt in the FAQ then it bloody well should be.
    You have two basic strategies.

    1) Get all input as a string and use stringstreams to parse whats needed from the string

    2) Use member functions of the cin object such as clear(),fail(),good(),bad() and ignore() to do the necessary.

    Check the FAQ. there should be examples in it.
    Free the weed!! Class B to class C is not good enough!!
    And the FAQ is here :-

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