Consider this C code to swap two integers and these five statements:
void swap(int *px, int *py)
{
*px = *px - *py;
*py = *px + *py;
*px = *py - *px;
}
S1: will generate a compilation error
S2: may generate a segmentation fault at runtime depending on the arguments passed
S3: correctly implements the swap procedure for all input pointers referring to integers stored in memory locations accessible to the process
S4: implements the swap procedure correctly for some but not all valid input pointers
S5: may add or subtract integers and pointers.