embedded

Let us declare const object as volatile and compile code with optimization option. Although we compile code with optimization option, value of const object will change, because variable is declared as volatile that means don’t do any optimization.

/* Compile code with optimization option */ #include <stdio.h> intmain(void) {     Const volatile int local = 10;     int*ptr = (int*) &local;     printf("Initial value of local : %d \n", local);     *ptr = 100;     printf("Modified value of local: %d \n", local);     return0; }

Output:

$ gcc -O3 volatile.c -o volatile –save-temp

$ ./volatile

  Initial value of local : 10

  Modified value of local: 100

If we do not use volatile qualifier, the following problems may arise
1) Code may not work as expected when optimization is turned on.
2) Code may not work as expected when interrupts are enabled and used