What are Inline functions?

What are Inline functions? How to define inline function and why ?
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The Inline keyword helps in speeding up programs by making very small functions execute more efficiently. A compiler compiles a new copy of the function each time it is called. However when you declare a function as inline, when the compiler expands a function call, the function's code gets inserted into the caller's code stream.

Essentially compiler will cut and paste the inline function wherever it is called in your program at compile time. Inline functions save the step of retrieving the function, at the cost of a larger compiled program. The MAX function is a typical (and good) example of a good time to use inline

cpp code

inline int MAX(int x, int y)
{
     return (x > y) ? x : y;
}