Do you not understand booleans?
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CDP1802 wrote:
why not if (flag == true)?
Indeed, I prefer that when writing in C. One thing that drives me nuts with C is reading things like:
char* s = ...
if ( s ) ...
:mad:
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This stuff drives me up the wall!!!
bool is_queue_empty(void)
{
if (queue_length==0)
{
return true;
}
else
{
return false;
}
}Or this:
bool counter_zero = counter==0 ? true : false;
Or this:
if (isUDPSetup()==true)
{
if ((forceSend==false))
{
...
}
}(Variable names have been changed to protect the guilty) Or this *New one*:
void setNeedsUpdate(bool update)
{
if ((update==true))
NeedsUpdate=true;
else
NeedsUpdate=false;
} -
And I think your reasoning would be wrong. It IS more clear to write if (X==true). Just because you don't like it does not mean it is not more clear, especially to junior programmers. I am the senior lead and I instruct ALL of our programmers under me to write if (X==true). It doesn't cost the compiler anything and it makes it understandable by even the junior most person quickly. It is all about proper maintenance and thinking about the coder behind you instead of just yourself. X is a variable so comparing it like another variable is both consistent and readable.
This is, at best, a matter of opinion. For me it is less clear to write if(x == true) because I have to read twice as much text to get the meaning &dnash; just as it's unclear to give a method a 300 character name. I have never met anyone who is confused by if(booleanVariable) and if they are then they shouldn't be programming until they learn the language they're using – if they have trouble reading that then do you really want them poking around your pointer code, or reflection in C#, or constructor injection frameworks, or any of the other million things any real world app has that are far more confusing? Readability is all about having a single, clear, unambiguous meaning for a statement as quickly as possible. if(x) and if(!x) are short, clear and obviously different from each other (as long as you're using a font where ! is more than 2 pixels wide, heh). if(x == true) adds nothing, is easier to mix up with closely related but different statements (if(x = true) or if(x == True) or if(x == "true") etc) and doesn't immediately show that x is a boolean or castable to one until you read the whole thing. You are on your way to becoming one of the micromanaging senior leads who appear on The Daily WTF issuing that kind of order based on your personal opinion of readability.
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Fine. Now what if a is a (signed) integer and has a negative value? Or what if a is a pointer which is currently NULL? Without having defined any value for TRUE or FALSE and without knowing how NULL was defined somewhere deep in the libraries, how do you now know which code will be executed and which not? Even if NULL is usually defined as 0x00, you cannot expect this to be true for every compiler. And what can happen if you use another compiler?
int* a = NULL;
int b = -42;if(a)
{
// We should not need to know how NULL is defined and therefore can never know wether
// or not this code block will ever be entered
}if(a == NULL)
{
// Now we explicitly compared with NULL and it is clear when this code will be executed
}if(b)
{
// Negative values are undefined and it is up to the compiler wether a negative value is
// seen as 'true' or as 'false'
}if(b < 0)
{
// Explicitly testing the variable again removes all uncertainties
}And from the clouds a mighty voice spoke:
"Smile and be happy, for it could come worse!"And I smiled and was happy
And it came worse.Hey, I went and looked this up, the standard states explicitly that "In both forms, the first substatement is executed if the expression compares unequal to 0." http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf[^] page 147 That is, negative numbers are defined by standard to be true for conditional expressions.
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And it obviously makes the reader scared of what else might come from that code who's developer can't understand even a booleans...
"To alcohol! The cause of, and solution to, all of life's problems" - Homer Simpson
i might be showing my age here but there used to be a readability test known as "the telephone test" (from Kerningham and Plauger) - Read your code to someone over the phone. If they can't understand it, try writing the code again. admittedly this has its problems but one of the upshots was that you should just name your booleans for the thing they test and then it reads well. also, comparing to "== true" or "== false" obviously breaks this readability test :)
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i might be showing my age here but there used to be a readability test known as "the telephone test" (from Kerningham and Plauger) - Read your code to someone over the phone. If they can't understand it, try writing the code again. admittedly this has its problems but one of the upshots was that you should just name your booleans for the thing they test and then it reads well. also, comparing to "== true" or "== false" obviously breaks this readability test :)
mostlyharmless1964 wrote:
i might be showing my age here
Wow, never heard of it. Was it the time when the compilers were birds inside stone cases? :laugh:
"To alcohol! The cause of, and solution to, all of life's problems" - Homer Simpson
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This stuff drives me up the wall!!!
bool is_queue_empty(void)
{
if (queue_length==0)
{
return true;
}
else
{
return false;
}
}Or this:
bool counter_zero = counter==0 ? true : false;
Or this:
if (isUDPSetup()==true)
{
if ((forceSend==false))
{
...
}
}(Variable names have been changed to protect the guilty) Or this *New one*:
void setNeedsUpdate(bool update)
{
if ((update==true))
NeedsUpdate=true;
else
NeedsUpdate=false;
}I fully agree. This kind of stuff makes the code SO hard to read. And so many people do this too - just look at all the examples you were able to find! Atrocious. When will people learn to put spaces around their operators !?!?! :cool:
Clive Pottinger Victoria, BC
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And I think your reasoning would be wrong. It IS more clear to write if (X==true). Just because you don't like it does not mean it is not more clear, especially to junior programmers. I am the senior lead and I instruct ALL of our programmers under me to write if (X==true). It doesn't cost the compiler anything and it makes it understandable by even the junior most person quickly. It is all about proper maintenance and thinking about the coder behind you instead of just yourself. X is a variable so comparing it like another variable is both consistent and readable.
Why do boolean variables exist? To store and retrieve boolean expressions (TRUTH values). They were invented SO THAT we can write code like
if (X)
otherwise we could just as well remove the boolean type and work with integer flags like
if (X==1)
This was one of the issues people had with C. No proper boolean type. But now we have a proper boolean type so don't reduce it to a "flag value" that needs to be compared to something to find the truth. It holds the truth all on its own. That's its job.
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This stuff drives me up the wall!!!
bool is_queue_empty(void)
{
if (queue_length==0)
{
return true;
}
else
{
return false;
}
}Or this:
bool counter_zero = counter==0 ? true : false;
Or this:
if (isUDPSetup()==true)
{
if ((forceSend==false))
{
...
}
}(Variable names have been changed to protect the guilty) Or this *New one*:
void setNeedsUpdate(bool update)
{
if ((update==true))
NeedsUpdate=true;
else
NeedsUpdate=false;
}Just ran across this in code I've been asked to maintain (no kidding):
if (((ucGlobalHeaterEnable & (1 << UC_BHOSE_HTR_ON) ) > 0) ? 1 : 0)
{
...
}Unbelievable!
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This stuff drives me up the wall!!!
bool is_queue_empty(void)
{
if (queue_length==0)
{
return true;
}
else
{
return false;
}
}Or this:
bool counter_zero = counter==0 ? true : false;
Or this:
if (isUDPSetup()==true)
{
if ((forceSend==false))
{
...
}
}(Variable names have been changed to protect the guilty) Or this *New one*:
void setNeedsUpdate(bool update)
{
if ((update==true))
NeedsUpdate=true;
else
NeedsUpdate=false;
}A true classic. I got thought to not do this first weeks in programming class, before learning stuff like functions.
Jeroen De Dauw (blog | Twitter | Identi.ca)
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Wouldn't this be more run-time efficient, as the value of
updatecan be cached in a register ?void setNeedsUpdate(bool update)
{
if (update == true)
{
NeedsUpdate= update;
}
else
{
NeedsUpdate= update;
}
};->
Or more straightforward:
void setNeedsUpdate(bool update)
{
NeedsUpdate = update;
}Less confusing, and same behavior.
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Or more straightforward:
void setNeedsUpdate(bool update)
{
NeedsUpdate = update;
}Less confusing, and same behavior.
What about this:
void setNeedsUpdate(bool update)
{
// Case anaylsis
if (update == (update == update))
{
// When update is true, flag the Update as Needed
NeedsUpdate= update;
}
else if (update == (update != update))
{
// Else when update is false, flag the Update as not Needed
NeedsUpdate= update;
}
else
{
// Else, when update is neither true nor false, assign an arbitrary value
NeedsUpdate= update;
}
}it has the advantage of using no constant at all and cleanly handles the case where
updateis not a boolean value. I have added enlightening comments. -
They were probable taught to program by some CS grad student who'd never done much significant real-world coding. That's right along the lines of the kinds of stupidity my teachers would teach us when I was an undergrad. Like everybody else, I picked up the stupidity too.. which lasted until I saw the other way and had to debug code to a schedule that was broken by such nonsense. I still do the compare to NULL sometimes, but I believe the C standard now defines NULL pointers as a false boolean value, so it is redundant and I'm trying to retrain away from it. Besides, boost smart pointers, which we use a lot in our code, have an override to generate a bool result for just such kinds of pointer checks and make comparing the raw pointer to NULL harder.
We can program with only 1's, but if all you've got are zeros, you've got nothing.
Personally, I don't promote the C rule that implicitly turns an expression to boolean based on zeroness, whatever the type. Because even though perfectly legal it looks like a quick & dirty shorthand to spare typing a comparison; and it can overload an identifier with two meanings, that of the numerical value (or address) and that of a condition, as if the variable had two data types. What would you think of this (fiddled) snippet:
int NoRetries; // Number of sending retries
NoRetries= SendMessage();
if (NoRetries)
{
// Investigate
}as opposed to
if (NoRetries > 0)
{
// Investigate
}C was lacking a boolean type in the old days, in my opinion a design flaw. That made the aforementioned rule perfectly relevant. I prefer making the booleans explicit and highlighted. In a moderatly pedantic style, this would give us
bool Retried= NoRetries > 0;
if (Retried)
{
// Investigate
} -
void setNeedsUpdate(bool update)
{
if ((update==true))
NeedsUpdate=true;
else
NeedsUpdate=false;
}This would be better if they returned it too. Nothing like getting back what you put into it.
bool setNeedsUpdate(bool update)
{
if ((update==true))
NeedsUpdate=true;
else
NeedsUpdate=false;
return NeedsUpdate;
}Excellent, in addition this provides a way to test that assignment succeeded and was correct. I would even suggest
bool setNeedsUpdate(bool update)
{
if ((update==true))
{
NeedsUpdate=true;
return NeedsUpdate;
}
else
{
NeedsUpdate=false;
return NeedsUpdate;
}
}so that if the code has a logic flaw, the function never returns ! ;)
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Just ran across this in code I've been asked to maintain (no kidding):
if (((ucGlobalHeaterEnable & (1 << UC_BHOSE_HTR_ON) ) > 0) ? 1 : 0)
{
...
}Unbelievable!
Rather indigestible indeed. I couldn't resist rewriting this piece using bit fields (in my opinion a sadly underused feature in C):
struct tGlobalHeaterEnable
{
bool bHoseHtrOn: 1;// More fields here...} sGlobalHeaterStatus;
if (sGlobalHeaterEnable.bHoseHtrOn)
{
// More code here...
} -
Personally, I don't promote the C rule that implicitly turns an expression to boolean based on zeroness, whatever the type. Because even though perfectly legal it looks like a quick & dirty shorthand to spare typing a comparison; and it can overload an identifier with two meanings, that of the numerical value (or address) and that of a condition, as if the variable had two data types. What would you think of this (fiddled) snippet:
int NoRetries; // Number of sending retries
NoRetries= SendMessage();
if (NoRetries)
{
// Investigate
}as opposed to
if (NoRetries > 0)
{
// Investigate
}C was lacking a boolean type in the old days, in my opinion a design flaw. That made the aforementioned rule perfectly relevant. I prefer making the booleans explicit and highlighted. In a moderatly pedantic style, this would give us
bool Retried= NoRetries > 0;
if (Retried)
{
// Investigate
}I absolutely agree with you and consider using the a-zero-int-value-is-a-bool-false feature of C/C++ to be sloppy. Valid, but sloppy. I consider it sloppy because 0 is a meaningful (and highly useful) value for an int. However, with pointers, NULL is a meaningful value that indicates the pointer points to nothing, all other values are considered valid pointers. Using a pointer like a bool and checking if it is explicitly NULL are the same -- they are both asking if it points to anything. There is no other possible semantic interpretation. Writing code that omits an explicit comparison to NULL is also more easier to upgrade if the pointer is switched to one of the boost smart pointer classes, something we've done a fair amount of over the years. Not that the compiler doesn't catch the now-invalid comparison, but then you have to touch all that code just to get the same semantic meaning.
We can program with only 1's, but if all you've got are zeros, you've got nothing.
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This stuff drives me up the wall!!!
bool is_queue_empty(void)
{
if (queue_length==0)
{
return true;
}
else
{
return false;
}
}Or this:
bool counter_zero = counter==0 ? true : false;
Or this:
if (isUDPSetup()==true)
{
if ((forceSend==false))
{
...
}
}(Variable names have been changed to protect the guilty) Or this *New one*:
void setNeedsUpdate(bool update)
{
if ((update==true))
NeedsUpdate=true;
else
NeedsUpdate=false;
}I'm with you on this one! Sometimes verbosity improves readability, but there are many cases where it's just dumb. The first example is terrible:
bool is_queue_empty(void)
{
if (queue_length==0)
{
return true;
}
else
{
return false;
}
}More code & multiple exit points -- for zero benefit???!!! X| This would be better:
bool is_queue_empty(void)
{
return queue_length == 0;
}:)
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I absolutely agree with you and consider using the a-zero-int-value-is-a-bool-false feature of C/C++ to be sloppy. Valid, but sloppy. I consider it sloppy because 0 is a meaningful (and highly useful) value for an int. However, with pointers, NULL is a meaningful value that indicates the pointer points to nothing, all other values are considered valid pointers. Using a pointer like a bool and checking if it is explicitly NULL are the same -- they are both asking if it points to anything. There is no other possible semantic interpretation. Writing code that omits an explicit comparison to NULL is also more easier to upgrade if the pointer is switched to one of the boost smart pointer classes, something we've done a fair amount of over the years. Not that the compiler doesn't catch the now-invalid comparison, but then you have to touch all that code just to get the same semantic meaning.
We can program with only 1's, but if all you've got are zeros, you've got nothing.
Sorry, no exception even for convenience. An integer is an integer, a pointer is a pointer and a boolean is a boolean.