The video tutorial explains the concept of the external storage class in C programming, focusing on the use of the 'extern' keyword. It describes how external variables are defined outside any function block and can be accessed globally across different source files within the same project. The tutorial provides an example with two files, demonstrating how to declare and use an external variable. It also covers the importance of declaring a global variable once in the project and how the compiler treats separate files as distinct compilation units. The tutorial concludes with a summary and a preview of the next lecture, which will involve practical implementation in Visual Studio.

What is the primary purpose of using the 'extern' keyword in C?

• To declare a global variable that is defined elsewhere

• To initialize a variable with a default value

• To define a constant value

• To declare a new local variable

In the given example, what is the initial value of the 'count' variable in the main program file?

• 20

• 15

• 10

• 5

Why is it necessary to declare the 'count' variable as 'extern' in the second file?

• To initialize the variable with a specific value

• To inform the compiler that the variable is defined in another file

• To ensure the variable is local

• To create a new variable

What will be the output of the program after the 'Foo' function is called?

• count equals 20

• count equals 5

• count equals 10

• count equals 15

How does the 'extern' keyword assist the compiler during the linking process?

• It allows the variable to be used only within the same file

• It prevents the variable from being used

• It helps the compiler link the variable definition across different files

• It automatically initializes the variable