Question

C PROGRAMMING LANGUAGE

The following code written in C programming language was run and displays 997705320. Explain why and how this program outputs this number.

int main(void) {

int a = 5, b =20;

int* ptr = &a;

int** ptr2 = &ptr;

printf("%d\n", ((int)*ptr * (int)*ptr2));

return 0;

}

Answer 1

The program :

int main(void) {

int a = 5, b =20;

int* ptr = &a;

int** ptr2 = &ptr;

printf("%d\n", ((int)*ptr * (int)*ptr2));

return 0;

}

EXPLANATION :

Here , ptr is the pointer that is pointing to the variable a . And **ptr2 is the double pointer which stores the address of pointer variable ptr.

And at each time when this code runs , the memory allocated to pointer ptr and ptr2 is different.

Hence when you runs this code, memory allocated to ptr is 199541064.

And so value of (int)*ptr is 5 as ptr is pointing to variable a. And the value of (int)*ptr2 is 199541064

printf("%d\n", ((int)*ptr * (int)*ptr2));

And the above statement will print : ( 5 * 199541064 ) = 997705320