C++ Tutorial/Development/Macro Expansion

function macro

<source lang="cpp">#include <iostream> using namespace std;

1. define getmax(a,b) ((a)>(b)?(a):(b))

int main() {

 int x=5, y;
 y= getmax(x,2);
 cout << y << endl;
 cout << getmax(7,x) << endl;
 return 0;

}</source>

Macro Expansion

<source lang="cpp">#include <iostream>

#define CUBE(a) ( (a) * (a) * (a) )
#define THREE(a) a * a * a

int main()
{
    long x = 5;
    long y = CUBE(x);
    long z = THREE(x);

    std::cout << "y: " << y << std::endl;
    std::cout << "z: " << z << std::endl;

    long a = 5, b = 7;
    y = CUBE(a+b);
    z = THREE(a+b);

    std::cout << "y: " << y << std::endl;
    std::cout << "z: " << z << std::endl;
    return 0;
}</source>

y: 125
z: 125
y: 1728
z: 82

standard macro names: __LINE__, __DATE__, __cplusplus

<source lang="cpp">#include <iostream> using namespace std; int main() {

 cout << "This is the line number " << __LINE__;
 cout << " of file " << __FILE__ << ".\n";
 cout << "Its compilation began " << __DATE__;
 cout << " at " << __TIME__ << ".\n";
 cout << "The compiler gives a __cplusplus value of " << __cplusplus;
 return 0;

}</source>