I am reading a C++ code and came across a function:
double Nm_poissons_ratio(double /*Temp*/) { double PR(0.0); PR = 0.31; return PR; } I don't understand what is the effect of /* */ characters which surround the Temp variable.
Thanks
- @ Ami, Cory & ARL: Thank you for the answer. It is interesting that in the function argument we have variable type but no variable; wondering how does compiler interpret this type of argument.gyan– gyan2015-06-19 20:42:05 +00:00Commented Jun 19, 2015 at 20:42
- There is a variable. It just doesn't have a name you can use.Lightness Races in Orbit– Lightness Races in Orbit2015-06-19 20:42:42 +00:00Commented Jun 19, 2015 at 20:42
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3 Answers
If you write
double Nm_poissons_ratio(double Temp) the compiler will warning. about an unused variable.
In this case, the coder wanted to retain the signature for some reason, but to avoid the warning. He/she therefore put a comment to show what it originally was.
Why is this the signature? It's hard to know.
Perhaps this is an intermediate version of the code, and he/she plans to use this parameter in the future (this is actually an excellent case to retain the warning).
Perhaps it's passed as a callback to some function that expects a specific signature.
1 Comment
gyan
Thank you for the answer. It is interesting that in the function argument we have variable type but no variable; wondering how does compiler interpret this type of argument.
It means that the function takes a double argument, but they are commenting out the name (hence the /* */) because the argument to be named.
Likely because the compiler will warn them about an unused formal argument, since they do not use Temp anywhere in the function.
Comments
All that is happening is the developer is commenting out a piece of code. Basically a comment tells the computer to ignore this piece of code. So, if you were developing a programming you would:
/* This is hidden to everyone BUT the programmer. */ 