How to use Macro argument as string literal?
C++C PreprocessorString LiteralsC++ Problem Overview
I am trying to figure out how to write a macro that will pass both a string literal representation of a variable name along with the variable itself into a function.
For example given the following function.
void do_something(string name, int val)
{
cout << name << ": " << val << endl;
}
I would want to write a macro so I can do this:
int my_val = 5;
CALL_DO_SOMETHING(my_val);
Which would print out: my_val: 5
I tried doing the following:
#define CALL_DO_SOMETHING(VAR) do_something("VAR", VAR);
However, as you might guess, the VAR inside the quotes doesn't get replaced, but is just passed as the string literal "VAR". So I would like to know if there is a way to have the macro argument get turned into a string literal itself.
C++ Solutions
Solution 1 - C++
Use the preprocessor #
operator:
#define CALL_DO_SOMETHING(VAR) do_something(#VAR, VAR);
Solution 2 - C++
You want to use the stringizing operator:
#define STRING(s) #s
int main()
{
const char * cstr = STRING(abc); //cstr == "abc"
}
Solution 3 - C++
#define NAME(x) printf("Hello " #x);
main(){
NAME(Ian)
}
//will print: Hello Ian
Solution 4 - C++
Perhaps you try this solution:
#define QUANTIDISCHI 6
#define QUDI(x) #x
#define QUdi(x) QUDI(x)
. . .
. . .
unsigned char TheNumber[] = "QUANTIDISCHI = " QUdi(QUANTIDISCHI) "\n";