In C language array has a fixed size meaning once the size is given to it, it cannot be changed i.e. you can’t shrink it neither can you expand it. The reason was that for expanding if we change the size we can’t be sure ( it’s not possible every time) that we get the next memory location to us as free. The shrinking will not work because the array, when declared, gets memory statically, and thus compiler is the only one to destroy it.
Types of indexing in an array:
- 0 (zero-based indexing): The first element of the array is indexed by a subscript of 0
- 1 (one-based indexing): The first element of the array is indexed by the subscript of 1
- n (n-based indexing): The base index of an array can be freely chosen. Usually, programming languages allowing n-based indexing also allow negative index values, and other scalar data types like enumerations, or characters may be used as an array index.
Advantages of using arrays:
- Arrays allow random access to elements. This makes accessing elements by position faster.
- Arrays have better cache locality that can make a pretty big difference in performance.
- Arrays represent multiple data items of the same type using a single name.
Disadvantages of using arrays:
You can’t change the size i.e. once you have declared the array you can’t change its size because of static memory allocated to it. Here Insertion and deletion are difficult as the elements are stored in consecutive memory locations and the shifting operation is costly too.
Now if take an example of implementation of data structure Stack using array there are some obvious flaw.
Example -
// A character array in C/C++/Java
char arr1[] = {'g', 'e', 'e', 'k', 's'};