Valadating letters

This is a discussion on Valadating letters within the C++ Programming forums, part of the General Programming Boards category; Hi guys, Below is my validation function, what it should do is check the length of num1 which is a ...

  1. #1
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    Valadating letters

    Hi guys,

    Below is my validation function, what it should do is check the length of num1 which is a string( bad name i know!) and also convert num1 to be a floating point number, then it should check to see if the length is less than or equal to 6, and in the range of 0 -1000,


    What i also need to do in this function is to check that no letters have been entered,

    Code:
    float validation1()           // validation1 function
             {
    
             length1 = strlen(num1);      // Finds out length of string
             convertnum1 = atof(num1);    // converts string to float
    
    
    
             if (length1 <= 6 && convertnum1 >= 0 && convertnum1 <= 1000) // check length & range
             {
             return convertnum1;
             }
    
             else
             {
             calc(); // calls calculation function
             }
             return 0;
             } // end of validation function

    Does anybody know how this could be achieved?

    i have heard of a function called isdigit(), would this be used?


    Thanks alot guys

    Boontune

  2. #2
    Registered User
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    first of all: kick out that ugly global vars!
    never ever use them

    there is a 'function' (actually it is often a macro) isdigit() in ctype.h

    it's easy to use: you call it with your char as param and it returns true (!0) if your char is a digit oder 0 otherwise

    and beware: atof returns double not float
    Hope you don't mind my bad english, I'm Austrian!

  3. #3
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    Thanks for the help...

    Boontune

  4. #4
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    What are the other two functions called with ctype.h?

    i now there is:

    isdigit() - for numbers

    isalpha() - for letters

    Can someone tell me what the other two are called?

    for puncutation and space?

  5. #5
    It's full of stars adrianxw's Avatar
    Join Date
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    Open your ctype.h file! You can see what there is in it, (and there are morew than two more).
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

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