Is sizeof for a struct equal to the sum of sizeof of each member?

Prerequisite : sizeof operator in C
The sizeof for a struct is not always equal to the sum of sizeof of each individual member. This is because of the padding added by the compiler to avoid alignment issues. Padding is only added when a structure member is followed by a member with a larger size or at the end of the structure.

Different compilers might have different alignment constraints as C standards state that alignment of structure totally depends on the implementation.

Let’s take a look at the following examples for better understanding:

C language doesn’t allow the compilers to reorder the struct members to reduce the amount of padding. In order to minimize the amount of padding, the struct members must be sorted in a descending order (similar to the case 2).

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