Inline functions

C++ inline function is powerful concept that is commonly used with classes. If a function is inline, the compiler places a copy of the code of that function at each point where the function is called at compile time.

Any change to an inline function could require all clients of the function to be recompiled because compiler would need to replace all the code once again otherwise it will continue with old functionality.

To inline a function, place the keyword inline before the function name and define the function before any calls are made to the function. The compiler can ignore the inline qualifier in case defined function is more than a line.

A function definition in a class definition is an inline function definition, even without the use of the inline specifier.

#include <iostream>

#include<conio.h>

inline void hello()
{
  cout<<"hello";
}
int main()
{
  hello(); //Call it like a normal function...
  getch();
}

Inline functions are very good for saving time, but if you use them too often or with large functions you will have a tremendously large program. Sometimes large programs are actually less efficient, and therefore they will run more slowly than before. Inline functions are best for small functions(WITHOUT USING CONTROL STATEMENTS) that are called often.

Finally, note that the compiler may choose, in its infinite wisdom, to ignore your attempt to inline a function. So if you do make a mistake and inline a monster fifty-line function that gets called thousands of times, the compiler may ignore you.