What is a pre-processor macro and how is it processed by the C++ system? Demonstrate a potential problem with this approach by referring to the macro
#define SQR(t) t*twhat is wrong here... besides the fact that if you put a type that cant use the * operator you'll get a compile time error
Jump to Postwhat is wrong here...
Side effects, my inquisitive friend:
int x = 2; cout<< SQR(x++) <<'\n'; cout<< x <<'\n';x is incremented twice due to the macro being nothing more than a textual substitution. Thus the expanded macro is
x++ * x++.
what is wrong here...
Side effects, my inquisitive friend:
int x = 2;
cout<< SQR(x++) <<'\n';
cout<< x <<'\n';x is incremented twice due to the macro being nothing more than a textual substitution. Thus the expanded macro is x++ * x++ .
That is not a very easy macro definition to demonstrate the other error but consider this code using that macro ~SQR(2) . What do expect the output to be, what is it?
This is normally more easily demonstrated with the macro in question uses + rather than *.
We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.