C Programming: Arrays

Study Notes

An array must be initialized when declared, or the compiler will show an error "size of array is unknown or zero".
There are four ways to initialize one-dimensional arrays in C programming:
- Initialize at the time of declaration, e.g., int a[] = {10, 20, 30, 40, 50};.
- Initialize all elements with 0 (zero).
- Initialize elements individually, e.g., int a; a = 10; a = 20; ....
- Define the size of an array by initializing its elements.

The return statement terminates the execution of a function and returns control to the calling function.
It can also return a value to the calling function.
The point of functions is to take in inputs and return something.

An array is a collection of elements of the same type placed in contiguous memory locations.
Array elements can be individually referenced by using an index to a unique identifier.

The extern storage class is used for global variables and functions shared between two or more files.
Extern variables are accessible throughout the program.
Extern variables cannot be initialized, as they have already been defined in the original file.

Static variables are used within functions/files as local static variables or as global variables.
Static local variables retain their value between function calls or block and remain visible only to the function or block in which they are defined.
Static global variables are global variables visible only to the file in which they are declared.
Static variables have a default initial value of zero and are initialized only once in their lifetime.