C Programming

Question

main()
{
unsigned int i= 255;
char *p= &i;
int j= *p;
printf("%d\n", j);
unsigned int k= *p;
printf("%d", k);
}

 

Both the outputs are -1. I have even tried with - int i = 255(3rd line). Still the output is -1.

I don't understand how it is -1.

Comments

%d is used to print signed values and %u for unsigned values..

---

thanks

Answer 1

I guess we saw that happening due to incompatible type casting.

When we use char *p = &i : due to signed / unsigned type casting (underflow) unsigned 255 becomes signed -1 hence the values of j and k.

Try to run below:

int main(){
    unsigned int i = 255;
    int *p = &i;
    int j = *p;
    
    unsigned int k = *p;
    
    printf ("i : %d \n", i);
    printf ("j : %d \n", j);
    printf ("k : %d \n", k);
    
    return 0;
}

Let me know your thoughts.