volatile keyword in c

The volatile keyword in C

In C, the volatile keyword is used to indicate that a variable may be changed at any time without the knowledge of the compiler. It informs the compiler that the value of the variable can be altered by external means, such as concurrently executing threads or hardware. As a result, the compiler should not optimize or cache the value of the variable.

The volatile keyword is typically used when working with memory-mapped I/O or when dealing with variables that can be modified asynchronously. By using volatile, the programmer ensures that the variable is always read from and written to memory, rather than being optimized by the compiler.

Here's an example of how the volatile keyword can be used in C:

volatile int sensor_reading = (volatile int) 0x12345678;
int current_value = *sensor_reading;

In this example, the variable sensor_reading is declared as volatile to indicate that its value may change at any time due to external factors. When reading the value of sensor_reading, the programmer ensures that the most up-to-date value is retrieved from memory.

By using the volatile keyword, the programmer can effectively convey to the compiler that certain variables should not be optimized in ways that assume their values will not change outside the control flow of the program.

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