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:

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  ShLogWrite("_CINSRCH", GbCEPSecurity);

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Code:

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char *boolstring( _Bool b ) { return b ? "true" : "false"; }

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Quzah.

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?

No, you can just copy mine. ;)


Quzah.

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:

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b ? "true" : "false"

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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.

Quote:

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

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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:

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ShLogWrite("_CINSRCH", GbCEPSecurity ? "true" : "false");

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I've never heard of boolean variables in C?

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.


Quzah.

Quote:

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Originally Posted by sahil_m

I've never heard of boolean variables in C?

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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.

Quote:

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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.

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If you include <stdbool.h>.

Thanks all for your responses.

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

Quote:

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gives the compiler the ability to use the most efficient representation for a boolean value for the target architecture.

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What do you mean by this?

http://www.eskimo.com/~scs/C-faq/q9.1.html