C Macro Example: ADD(x) - Adding a Value to Itself

The code defines a macro 'ADD(x)' which takes an argument 'x' and returns 'x + x'.

The 'main' function initializes three integer variables 'm', 'n', and 'k' with the values 1, 2, and 3 respectively.

Then, it calculates the sum by using the 'ADD' macro with the expression 'm + n' and multiplies the result by 'k'.

Finally, it prints the value of 'sum' using 'printf'.