Thread: isalpha

  1. #1
    Just because ygfperson's Avatar
    Join Date
    Jan 2002


    any ideas on what's wrong with this segment? (it compiles in a program, but it doesn't work like it should)

    #define isalpha_alternate(x) (((x>='a' && x<='z')||(x>='A' && x<='Z')?1:0))

  2. #2
    train spotter
    Join Date
    Aug 2001
    near a computer
    Is it the braces?
    #define isalpha_alternate(x) (((x>='a' && x<='z')||(x>='A' && x<='Z'))?1:0)
    "Man alone suffers so excruciatingly in the world that he was compelled to invent laughter."
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  3. #3
    Registered User breed's Avatar
    Join Date
    Oct 2001
    what are you aiming to acheive?
    isalpha() already determine wether the data is a char,
    if your aim is to print uppercase the char or print to lower case char's

    first test for a char

    char ch;

    printf("Enter a letter >");
    scanf("%c", &ch);

    if( ch == isalpha(ch))
    //other test
    printf("\nthe letter is not a character");

    Before you judge a man, walk a mile in his
    shoes. After that, who cares.. He's a mile away and you've got
    his shoes.
    ************William Connoly

  4. #4
    Code Goddess Prelude's Avatar
    Join Date
    Sep 2001
    This works fine for me, be careful what kind of input you pass to the macro and put parens around the variables to ensure it works correctly with strange input.
    #include <stdio.h>
    #include <stdlib.h>
    #define isalpha_alternate(x) ((x) >= 'a' && (x) <= 'z'||(x) >= 'A' && (x) <= 'Z') ? 1 : 0
    int main(void)
      char ch = 'M';
      printf( "%d\n", isalpha_alternate( 'g' ) );
      printf( "%d\n", isalpha_alternate( ch ) );
      printf( "%d\n", isalpha_alternate( '7' ) );
      return EXIT_SUCCESS;
    My best code is written with the delete key.

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