CPP

c++ preprocessor operations

//INCLUDING BUILT-IN LIBRARIES...
#include <iostream>
#include <stdlib.h>
//PRE-DEFINE CONSTANT VALUES...
#define MAXNUM -12    //defining an integer
#define PI 3.1415     //defining a float
#define END "

		Program has ended!!
"   //defining a string
//PRE-DEFINING CONSTANT OPERATIONS...
#define ADD(a, b, c) (a + b + c)    //Operation that will add its 3 parameters

using namespace std;

int main(){
    //using other definitions to check if the current device is Windows or UNIX
    #ifdef _WIN32  
        cout<<"Windows Operating System Detected"<<endl;
    #elif __unix__
        cout<<"UNIX Operating System Detected"<<endl;
    #else
        cout<<"Operating System could NOT be identified!"<<endl;
    #endif
    
    cout<<endl<<"Using pre-defined values and operations: "<<endl;
    cout<<" • MAXNUM: "<<MAXNUM<<endl;       //using pre-defined integer
    cout<<" • PI: "<<PI<<endl;               //using pre-defined float
    cout<<" • ADD(): "<<ADD(2,5,99.5)<<endl;   //using pre-defined function

    cout<<END;    //using pre-defined string
    return 0;
}

c++ preprocessor commands

#include <iostream>
using namespace std;

#define PI 3.14159

int main () {
   cout << "Value of PI :" << PI << endl; 

   return 0;
}