Inline Functions and File Programs in C++

Inline Functions
#include <iostream.h>
const float Pi = 3.1415926;
inline float area(const float r) {return Pi * r * r;}
main()
{
float radius;
cout << "Enter the radius of a circle: ";
cin >> radius;
cout << "The area is " << area(radius) << "\n";
return 0;
}


File handling
#include <fstream.h>
int main()
{
char ch;
ifstream f1 ("OLDFILE.TXT");
ofstream f2 ("NEWFILE.TXT");
if (!f1) cerr << "Cannot open OLDFILE.TXT for input";
if (!f2) cerr << "Cannot open NEWFILE.TXT for output";
while (f2 && f1.get(ch))
f2.put(ch);
return 0;
}