how to detect a lowercase or uppercase char?

This is a discussion on how to detect a lowercase or uppercase char? within the C Programming forums, part of the General Programming Boards category; the tolower(char) toupper(char) functions can be used to convert a char to an upper or lower case. I wanted to ...

  1. #1
    Learner Axel's Avatar
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    how to detect a lowercase or uppercase char?

    the tolower(char) toupper(char) functions can be used to convert a char to an upper or lower case. I wanted to use these functions together with a char array, if the character in the array is lower case then convert it to upper case. But i'm not sure how to tell if the character in the array is upper or lower case to run the appropriate function.. any ideas?

  2. #2
    Super Moderator
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    ctype.h also contains the functions
    Code:
    int isupper(char c);
    int islower(char c);

  3. #3
    Just Lurking Dave_Sinkula's Avatar
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    Testing may be unnecessary.
    Code:
    #include <stdio.h>
    #include <ctype.h>
    
    int main(void)
    {
       char text[] = "abc 123 DEF !@#";
       size_t i;
       puts(text);
       for (i = 0; text[i] != '\0'; ++i)
       {
          text[i] = toupper(text[i]);
       }
       puts(text);
       return 0;
    }
    
    /* my output
    abc 123 DEF !@#
    ABC 123 DEF !@#
    */
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  4. #4
    & the hat of GPL slaying Thantos's Avatar
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    Quote Originally Posted by sean_mackrory
    ctype.h also contains the functions
    Code:
    int isupper(char c);
    int islower(char c);
    Actually the parameters are int not char

  5. #5
    Super Moderator
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    The author of C++ 5 for Dummies wasn't specific.

  6. #6
    & the hat of GPL slaying Thantos's Avatar
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    Yeah but the standard sure is

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