Adding 1 to "point" will now cause it to point to the second field of the array because of the way pointers are handled in C. The system knows that the structure contains three variables and it knows how many memory elements are required to store the complete structure. Therefore if we tell it to add one to the pointer, it will actually add the number of memory elements required to get to the next element of the array.
If, for example, we were to add 4 to the pointer, it would advance the value of the pointer 4 times the size of the structure, resulting in it pointing 4 elements farther along the array.
This is the reason a pointer cannot be used to point to any data type other than the one for which it was defined. Now to return to the program displayed on your monitor. It should be clear from the previous discussion that as we go through the loop, the pointer will point to the beginning of one of the array elements each time. We can therefore use the pointer to reference the various elements of the structure. Referring to the elements of a structure with a pointer occurs so often in C that a special method of doing that was devised. Using "point->initial" is the same as using "(*point).initial" which is really the way we did it in the last two programs. Remember that *point is the data to which the pointer points and the construct should be clear. The "->" is made up of the minus sign and the greater than sign.
Since the pointer points to the structure, we must once again define which of the elements we wish to refer to each time we use one of the elements of the structure. There are, as we have seen, several different methods of referring to the members of the structure, and in the for loop used for output at the end of the program, we use three different methods. This would be considered very poor programming practice, but is done this way here to illustrate to you that they all lead to the same result. This program will probably require some study on your part to fully understand, but it will be worth your time and effort to grasp these principles.
Compile and run this program.
If, for example, we were to add 4 to the pointer, it would advance the value of the pointer 4 times the size of the structure, resulting in it pointing 4 elements farther along the array.
This is the reason a pointer cannot be used to point to any data type other than the one for which it was defined. Now to return to the program displayed on your monitor. It should be clear from the previous discussion that as we go through the loop, the pointer will point to the beginning of one of the array elements each time. We can therefore use the pointer to reference the various elements of the structure. Referring to the elements of a structure with a pointer occurs so often in C that a special method of doing that was devised. Using "point->initial" is the same as using "(*point).initial" which is really the way we did it in the last two programs. Remember that *point is the data to which the pointer points and the construct should be clear. The "->" is made up of the minus sign and the greater than sign.
Since the pointer points to the structure, we must once again define which of the elements we wish to refer to each time we use one of the elements of the structure. There are, as we have seen, several different methods of referring to the members of the structure, and in the for loop used for output at the end of the program, we use three different methods. This would be considered very poor programming practice, but is done this way here to illustrate to you that they all lead to the same result. This program will probably require some study on your part to fully understand, but it will be worth your time and effort to grasp these principles.
Compile and run this program.
