c - Memory allocated without allocation using malloc, how?

Question

Below is a simple code snippet:

int main()
{
int *p;
p=(int*)malloc(sizeof(int));//allocate m/y 4 1 int 
printf("P=%p	Q=%p",p,p+2);
}

In one sample run, it gave me the output as below:

P=0x8210008 Q=0x8210010

Starting address of P is-P=0x8210008,next byte is 0x8210009,next byte is 0x821000A,next byte is 0x821000B.So the 4 bytes for int is ending there. We haven't allocated more memory using malloc. Then how is p+2 leading us to 0x8210010,which is 8 bytes after P(0x8210008).

Answer 1

Because it's treating it as an integer-element offset from the pointer. You have allocated an array for a single integer. When you ask for p+2 it's the same as &p[2]. If you want two bytes from the beginning, you need to cast it to char* first:

char *highWordAddr = (char*)p + 2;