How to Use the Volatile Keyword in C?

In C, the volatile keyword is used to inform the compiler that the value of a variable may change at any time, without any action being taken by the code in the program. It is particularly useful in embedded systems, signal handlers, and multi-threaded applications. In this article, we will learn how to use the volatile keyword in C.

Volatile Keyword in C

We can use the  for different purposes like declaring some global variables, signal handlers, variables across shared threads, etc. When a variable is declared as volatile, it tells the compiler:

• The compiler must not assume the value of the variable remains constant between accesses, so it should read the value from memory every time it is used.
• The compiler must not reorder instructions in a way that changes the access order of the volatile variable.

Syntax to Use Volatile Qualifier in C

volatile dataType varName;

C Program to Demonstrate the Use of Volatile Keyword

The below program demonstrates the use of volatile keyword in C.

Output

Final value of volVar: 20