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Inlines inside classes
To define an inline function, you must
ordinarily precede the function definition with the inline keyword.
However, this is not necessary inside a class
definition. Any function you
define inside a class definition is automatically an inline. For
example:
//: C09:Inline.cpp
// Inlines inside classes
#include <iostream>
#include <string>
using namespace std;
class Point {
int i, j, k;
public:
Point(): i(0), j(0), k(0) {}
Point(int ii, int jj, int kk)
: i(ii), j(jj), k(kk) {}
void print(const string& msg = "") const {
if(msg.size() != 0) cout << msg << endl;
cout << "i = " << i << ", "
<< "j = " << j << ", "
<< "k = " << k << endl;
}
};
int main() {
Point p, q(1,2,3);
p.print("value of p");
q.print("value of q");
} ///:~
Here, the two constructors and the
print( ) function are all inlines by default. Notice in
main( ) that the fact you are using inline functions is transparent,
as it should be. The logical behavior of a function must be identical regardless
of whether it’s an inline (otherwise your compiler is broken). The only
difference you’ll see is in performance.
Of course, the temptation is to use
inlines everywhere inside class declarations because they save you the extra
step of making the external member function definition. Keep in mind, however,
that the idea of an inline is to provide improved opportunities for
optimization by the compiler. But inlining a big
function will cause that code to be duplicated everywhere the function is
called, producing code bloat that may mitigate the speed benefit (the only
reliable course of action is to experiment to discover the effects of inlining
on your program with your
compiler).
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