What is padding in C?

In C what is meant by padding of bits? Consider the following structure,

struct number {
int a;
char b;
int c;
};


What is the size of this structure? An integer takes 4 bytes, char takes 1 and the third integer 4 bytes. Total 9 bytes. This is wrong. We can see the size of the structure is 12 bytes. What happens here? the compiler pads 3 bytes to char element. This is for proper alignment. In a 32 bit processor it checks the next data only after 32 bits. Else the compiler will have related problems. Now the compiler knows each data is 4 bytes wider. So the benefits.

Author: Abhilash

Hey! This is Abhilash - A Ruby developer for years, specialised on web development. Right now working as a freelance Ruby Developer. I am also working on Angular, Sinatra and many other backend infra. Mainly working on Ruby On Rails platform since 2010. This blog is about Ruby, Ruby On Rails and other subjects that I had a chance to go through. You can contact me here: abhilash.amballur@gmail.com Abhilash AK

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