Thread: boolean question

  1. #1
    Registered User
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    Jul 2004

    boolean question

    Given a function definition within a project as such:

    void usart_str_write(const char* string)
         while (*string)
    If string pointer sees anything other than a null, would it return a boolean true within the while loop condition? And is null character equivalent to a boolean false?


  2. #2
    Technical Lead QuantumPete's Avatar
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    Aug 2007
    London, UK
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  3. #3
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    If string is NULL, then anything can happen when you try to dereference it, so I'd make that part of the condition.

    > And is null character equivalent to a boolean false?
    0, '\0' and NULL are regarded as false in C.
    Any other integral value, any other character and any valid pointer are regarded as true.
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  4. #4
    Registered User
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    Jul 2004
    The reason that I'm asking the question is that I initially had *string != '\0'; as part of the condition.

  5. #5
    Kernel hacker
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    Farncombe, Surrey, England
    That would do exactly the same thing as the code you have now - no difference in behaviour.

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