Implementation of Inline Function in C++: Explained

Inline function in C++

Ever wonder why do we use functions? Simple, because it helps in saving the memory space. It becomes even more helpful in the case when it is called even more times. But whenever the function is called, a lot of time is taken in completing various tasks like moving to the calling function. If the function is small, a very fair amount of time gets used in likewise overheads, and the time taken to move to the calling function is higher than the time consumes in completing that function.

So how do you solve this problem? By using a macro definition like macros. In C, Preprocessor macros are quite popular. However, the main drawback of it is that they are not functions. Hence, you cannot find the usual error checking process does during compilation.
There is a tad-bit different solution in C++ for this problem. If you wish to remove the call time to small functions, a new function is proposed by C++ - inline function. This is the function that is expanded in line at the time it is being invoked, thereby helping in saving time. The function call is replaced by the compiler with the respective function code, which decreased the overhead of function calls.
It should be noted that inlining is simply a request made to the compiler. It is not a command. The request fro inlining can be ignored by the compiler, and it may not execute inlining in these circumstances:
If a function is recursive.
If a function contains a loop. (for, while, do-while)
If a function contains a switch command or goto statement.
If a function contains static variables.
For a function not returning values, if a return statement exists.
Syntax:
For an inline function, declaration and definition must be done together.
inline function-header
{
function-body
}
Example:
#include <iostream>
using namespace std;
inline int cube(int s)
{
return s*s*s;
}
inline int inc(int a)
{
return ++a;
}
int main()
{
int a = 11;
cout << "The cube of 3 is: " << cube(3) << "n";
cout << "Incrementing a " << inc(a) << "n";
return 0;
}
Output:
The Cube of 3 is: 27
Incrementing a 12
[Finished in 2.1s]

When to use Inline function?

The Inline function can utilize as the need. To check some of the important recommendations, read ahead -

• When you need the performance is required, you may use the inline function.
• The inline function can be used over macros
• It is more preferred to use the inline keyword outside of the class with the function definition so as to hide the details of the function implemented.

Points to be remembered when utilizing Inline functions

• We should keep inline works little; little inline capacities have better productivity and excellent outcomes.
• Inline capacities do build productivity. However, we ought not to turn every one of the sizes inline. Provided that we make huge functions inline, it might prompt code swell and may wind up diminishing the productivity.
• It is prescribed to characterize huge capacities outside the meaning of a class utilizing extension goals:: administrator, provided that we describe such capabilities inside a class definition; at that point, they may become inline naturally and again influencing the effectiveness of our code.

What are the advantages of Inline function?

• Function call overhead never occurs.
• It spares the overhead of an arrival call from a capacity.
• It spares the overhead of push/pop factors on the stack when the capacity is called.
• At the point when we utilize the inline work it might empower the compiler to perform setting specific enhancement on the capacity body, such improvements are impractical for ordinary capacity calls.
• It expands the region of reference by using the guidance reserve.
• An inline capacity might be helpful for inserted frameworks because inline can yield less code than the ability to call prelude and return.