Undefined behaviour of const

Question

I never thought I will be going to ask this question but I have no idea why this happens.

const int a = 3; 
int *ptr;
ptr = (int*)( &a );
printf( \"A=%d\         


        

Answer 1

In fact your program invokes undefined behavior because of two reasons:
1.You are printing an address with wrong specifier %d. Correct specifier for that is %p.
2.You are modifying a variable with const specifier.

If the behavior is undefined then anything could happen. You may get either expected or unexpected result.
Standard says about it;

3.4.3 undefined behavior

behavior, upon use of a nonportable or erroneous program construct or of erroneous data, for which this International Standard imposes no requirements