Casting boolean as string

This is a discussion on Casting boolean as string within the C Programming forums, part of the General Programming Boards category; Didn't think I'd be back again this quickly, guess my recall isn't what I'd hoped it would be. How do ...

  1. #1
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    Casting boolean as string

    Didn't think I'd be back again this quickly, guess my recall isn't what I'd hoped it would be.

    How do a write the value of a boolean variable to a log as a string? I'd like to see the word 'True' or 'False' in my log.

    This code is giving me a compile warning of:

    different types for formal and actual parameter 2

    because the second parameter I'm passing is a Boolean and it's expecting a string. So I guess I'm asking, how do I cast the boolean variable GbCEPSecurity as a String?

    Code:
       ShLogWrite("_CINSRCH", GbCEPSecurity);

  2. #2
    ATH0 quzah's Avatar
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    Code:
    char *boolstring( _Bool b ) { return b ? "true" : "false"; }
    Quzah.
    Hope is the first step on the road to disappointment.

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    Thanks for your response but I'm not following that at all man.

    Are you saying I need to write my own function to do this?

  4. #4
    ATH0 quzah's Avatar
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    No, you can just copy mine.


    Quzah.
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  5. #5
    Sr. Software Engineer filker0's Avatar
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    quzah is correct, but not entirely helpful in this case

    What quzah gave you will work, but if you don't understand what his code does, it won't help you in solving the problem in the future.

    The construct
    Code:
    b ? "true" : "false"
    is a conditional expression where if the value of b (which can be an arbitrary boolean expression) is true, the value of the construct is the expression following the question mark (in this case, a pointer to a nul terminated char array containing the string "true"), and if b is false the expression has the value of the expression following the colon (in this case, a pointer to a nul terminated char array containing the string "false"). Look up "conditional expression" in your C language reference.

    Are you saying I need to write my own function to do this?
    The answer to this is "no". You can simply use a conditional expression wherever you want to do the conversion of a boolean to a string. If you do it more than once, though, a function will be more code-space efficient. You could write your code as:
    Code:
    ShLogWrite("_CINSRCH", GbCEPSecurity ? "true" : "false");

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    I've never heard of boolean variables in C?
    Thanks,
    Sahil

  7. #7
    ATH0 quzah's Avatar
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    C99 standard introduces them. The type is _Bool but it is aliased via a macro to bool for those who want to use it that way.


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  8. #8
    Sr. Software Engineer filker0's Avatar
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    Quote Originally Posted by sahil_m
    I've never heard of boolean variables in C?
    Pre-C99 versions of the C language standard don't have a built-in boolean type, but any expression that can be evaluated to a "true" or "not true" value, which usually means zero or not zero (NULL counts as zero) can be used. A simple integral variable, with no logical operators, can be considered a boolean expression, as its value is either 0 (false) or 1 (true). The addition of a boolean type in the most recent version of the standard allows for strong type checking and gives the compiler the ability to use the most efficient representation for a boolean value for the target architecture.

  9. #9
    Frequently Quite Prolix dwks's Avatar
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    The type is _Bool but it is aliased via a macro to bool for those who want to use it that way.
    If you include <stdbool.h>.
    dwk

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    Thanks all for your responses.

    filker0, thanks for your explanation and example; exactly what I needed on both accounts.

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    gives the compiler the ability to use the most efficient representation for a boolean value for the target architecture.
    What do you mean by this?
    Thanks,
    Sahil

  12. #12
    Just Lurking Dave_Sinkula's Avatar
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    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.*

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