While learning C Programming Language, you might have gone through the Function Concept. However, you might be unaware of the “Inline Functions In C” as for this you have to deep dive into the C Function which you have might not done.
Inline Functions are a separate branch of the Normal C Function concept. If you want to make your code concise and optimize the code to get the best result within a very short time, then working on Inline Function Call in C Language will be a necessity.
In this article, we will discuss the Inline Function along with its different types. Also, we will use the C language to practically show how the Inline Function Call works. So, let us start our discussion.
Summary or Key Highlights:
The Inline Function is a branch of the Normal C Function which is used rarely.
The Inline Function doesn’t generate the Memory Stack, hence optimizes the object code size to function faster.
Inline Definition can be done with the help of the Inline Keyword.
The Inline Keyword can’t be directly used in the C Codes but with the help of the Inline Function Specifier.
Static Inline and Extern Inline are the Inline Specifier which shares the same translation unit.
How To Use Inline Keyword In Program? Read Below
Now, that the concept of Inline Functions has become clear to you, we can proceed with the practical implementation process. Here, the implementation defined is using the above syntax and going to face an error. So, let us check the whole program below.
#include <stdio.h> // Declaration Of Standard Refers of Header File
inline int zap(int a, int b) // Declaration Of Function Inline
{
return a+b; // Inline Function Body
}
int main() // Main Function
{
int one = zap(2,3); // Inline Function Call
printf("The Result: %d", one); // Printing Of Result By Compiler
return 0;
}
Steps Of The Code:
The Inline Definition of Function Add() is done with the help of the Inline Keyword.
Inside that function, the Return Value is set to return the Result to the main function.
From the Main Function, Inline Function Calls will be performed.
At that same step, the compiler will perform inline substitution of the entire function’s code.
And at last, we are trying to print the value.
Output:
From the above output, we can see we are getting an Error Message on the screen. Here, the function declared in the code is working completely fine. However, as this is the Inline Function, the Add() Function is getting copied in the Main Function during Function Calls.
Hence, the Add() Function becomes the Non-Inline Function. That is the reason, we are getting the error.
What Are Two Types Of Inline Functions To Escape Errors?
Now, in the above section, you have seen how In-line Functions are becoming a Non-inline definition in the Usual Function (Main Function). Hence, we are getting an error which is not accepted. So, what will be the strategy where all the declarations of the storage class will not marked as Non-Inline?
If you don’t want to get errors, you have to use the Specifier as soon as you mention inline. There are two types of Specifiers present, hence, we can say there are two different types of In-line Functions present. Let us check them in the following section.
Static Inline Function Call: Static Functions are the special method that helps to make the entire source code written in the function as the Static. This makes the variables declared in the function executable in the Main function or somewhere else it is being called by the compiler.
Non-Static Inline Function Or Extern Inline Function Call: Here, the external definition will work. We have to use the Extern Keyword in this section this will make the entire code size available to access from the outside of the code.
How To Implement Static Inline Functions In C Language?
Now, we have seen how we are getting errors when we are simply using the Inline Functions. Now, it is time to use the Static Keyword to check the output. So, let us have a look at the following code and know how the C Compiler works here.
#include <stdio.h> // Declaration Of Standard Header File
static inline int zap(int a, int b) // Function Inline Declaration
{
return a+b; // Returning Addition Value Of Static Variables
}
int main() // Main Function
{
int one = zap(3,20); // Calling Inline Function
printf("The Static Inline Result: %d", one); // Printing Of Result By Compiler
return 0;
}
Steps Of The Code:
At first, the definitions of the Inline Function along with Static are completed.
Inside that function, some evaluation will be done and the value will be returned.
Now, the definitions of the Main Function will be done where we will Call Site.
At last, we will try to print the values in the output.
Output:
Now, you can see that the output is coming into the screen as we want. So, the program execution is completed and we have successfully debugged the Inline Function Call Error in the above-mentioned program with a simple Static Inline Keyword.
How To Implement Extern Inline Functions In C Language?
Now, after the Static, we will move to the External Definition. In normal cases, the definitions of Extern Keyword don’t go with the Inline Keyword. So, if you use an Extern Keyword with the Inline Function, it will become a normal function. To make an Extern Function an Inline one, you have to use one trick.
#include <stdio.h>
extern int zap(int a, int b); // Defined Of External Function Without Inline
int main() {
int one = zap(5, 14); // Providing Values
printf("The Extern Inline Result: %d", one);
return 0;
}
int zap(int a, int b) { // Defined The Same Function For External Definition
return a + b; // Addition Of Result By Compiler
}
Steps Of The Code:
At first, the definitions of Extern Function will be done without using the Inline() Keyword.
Now, inside the Main Function, the values are provided to the function for execution.
We will print the result in the Main Function.
At the end, the Normal Function will be declared with the same name.
Output:
From the above output, we can see that the result is coming usually as it comes. So, the Extern Keyword works as per the need of the code. So, the Inline Extern Function execution completes with the result.
What Is Translation Unit In Inline Function?
Now, after discussing all of the implementation processes, we have to move to the discussions on the Translation Unit before wrapping up the topic. Understanding the Translation Unit is essential to explain the behaviors of Functions in different files.
If any small functions or small part of the object code is considered as the Single Entity by the compiler will be known as the Translation Unit or Single Translation Unit. In C Programming Language, you will find different Translation Units like the following ones.
Source File: The Source File is one translation unit that multiple times is being used. In any C Compiler, the one translation unit of Source Files which is denoted as the (.C) is highly used before compiling the Object Code.
Header Files: The Header Files are also known as the Two Translation Units. Among many other translation units, the library file is used more in the C Compiler. Every Header File can have multiple translation units as per the need.
Preprocessor Directives: To make any source code final executable, the need to use the Directives is very much necessary which also falls under the translation unit. It directs the compiler the way it will execute the code to get input and output.
What Is Linkage In Inline Functions?
After discussing the Translation Units, it is time to discuss the Linkage in Inline Functions. These linkages will also control the Functions’ executions in different files. The use of the Linkage depends upon the use of the certain Inline Specifier.
If we do not use the Specifier with the Function definition, we are going to face the Linker Error. So, to bypass the Linker Errors, it is always a good practice to use the Linkage in Inline Functions. Based on the number of specifiers, we have the following two kinds of linkages.
Internal Linkage: The first one is the Internal Linkage where the Inline Function suggests using a Static Keyword. If you have done the Internal Linkage, it will get hidden from the Translation Units and it can’t be accessed from outside of the stand-alone object code.
External Linkage: If you want to achieve the External Linkage or External Definition, then you have to go for the Extern Inline Declaration with the Extern Keyword. As it is a non-static inline function, it can be accessed from outside of the stand-alone object code.
What Are Some Best Practices Of Inline Functions?
Now, before wrapping up we would like to discuss some best practices that you have to follow. Such suggestions will help to understand the concepts well and these are a few tips that will help to shape your practice ground on Inline Functions.
Mark Important Function: Identify the functions that are highly important for the execution of the code. Make Inline only those functions not any other.
Donโt Overuse: There is no need to use the Inline Function more times in the code. As many times, you will add the Inline Function, the code size will be increased.
Make Short Functions: When you have determined to make any function as the Inline Function, make their code small enough. You should not put Inline for Large Function.
Conclusion:
In the end, we can say knowing “Inline Functions In C” is very crucial for your future career.
If the concept of the Inline Function is clear to you, then you can easily do the code optimization. This will provide you with an extra benefit before starting the Algorithm concept. You have to practice the Inline Functions as much as possible to understand its working process.
Without clearing the basic C language, you should not move for this concept. Curious about learning C programming then here is the guide to start learning C in 5 easy steps.
Takeaways:
The Inline Function can be marked using the Keyword Inline in any certain Function.
If the Inline Function is providing errors, we have to use the Specifiers in the program.
We can’t use the Extern Keyword and Inline Keywords at the same time.
The combined use of the Extern & Inline Keywords will make the function a normal one.
