C programming

Declaring Variable as volatile

In C, the volatile keyword is used to indicate that a variable may be changed unexpectedly by the program, such as by hardware or by other parts of the program that the compiler may not be aware of. This prevents the compiler from applying certain optimizations that might not be safe when dealing with such variables. Here's an example to illustrate the use of volatile:

                    #include <stdio.h>

                        int main() {
                            volatile int sensor_value = 0;
                            while (1) {
                                // Assume sensor_value is changed by hardware
                                // and not by code the compiler can see.
                                printf("Sensor value: %d\n", sensor_value);
                            }
                            return 0;
                        }

In this example, sensor_value is marked as volatile because its value might change due to hardware (like a sensor updating its value), and the compiler should not make assumptions about its value being constant.

Resources :

Featured

Special title treatment

With supporting text below as a natural lead-in to additional content.

Q1. When is it appropriate to use the volatile keyword in C?

A When declaring a constant

B When optimizing code for speed

C When a variable may be modified asynchronously, e.g., by hardware

D When defining a function parameter

Q2. When should you use the volatile keyword for a variable in C?

A When the variable is assigned a constant value

B When the variable is shared between multiple threads or accessed by an interrupt service routine

C When the variable is only used within a single function

D When the variable is used for loop counters

Getting Started With C

Declaring Variable as volatile

Resources :

Special title treatment