what is a inline function in cpp code example

Example 1: c++ inline

#include<iostream>
/* When a function will be called repetitively, The "inline" keyword is used for 
optimization. The inline function tells the compiler that every instance of
this function should be replaced with the line or block of code in the body of the function;
This makes the compiler skip the middle-man, the function itself!

Important note: this method of optimization saves very little space, but it is still good practice.

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*/
inline void PrintEverySecond(string str) 
{
std::cout << str;

int main()
{
string Message = "Inline!" 
PrintEverySecond(Message); 
}
  // Unimportant note: this code obviously won't print every second since in isn't in a loop. This code is just a simple demo!

Example 2: inline c++

A function specifier that indicates to the compiler that inline substitution 
of the function body is to be preferred to the usual function call 
implementation