Another Question about pointers

[WarKirby]

I'm a little confused about an aspect of declaring pointer type variables. Not so much the what, as the why.

The tutorial says This:

"Due to the ability of a pointer to directly refer to the value that it points to, it becomes necessary to specify in its declaration which data type a pointer is going point to. It is not the same thing to point to a char than to point to an int or a float."

The problem I have with this, is that I don't understand WHY it is not the same thing, to point to different types of variables.

I understand that different types occupy different amounts of memory, but as I understand, a pointer holds a number, which is the first memory cell used.by that variable.

Therefore, I can't see why pointers would be anything more than an integer. Do they also hold data on the size of the memory block referred to? if so, why?

[Ganon11]

They do and don't. They do find out the size of the data type they point to so that they work properly in pointer arithmetic. For instance, take a look at this code:

int myIntArray[10];
int *myIntPointer = myIntArray; //myIntPointer now points to the first element in myIntArray
*myIntPointer; // first element
*(myIntPointer+3); // third element
myIntPointer - (myIntPointer + 3); // Should be 12, or 3 * sizeof(int)

double myDoubleArray[10];
double *myDoublePointer = myDoubleArray; //myDoublePointer now points to the first element in myDoubleArray
*myDoublePointer; // first element
*(myDoublePointer+3); // third element
myDoublePointer - (myDoublePointer + 3); // Should be 24, or 3 * sizeof(double)

char myCharArray[10];
char *myCharPointer = myCharArray; //myCharPointer now points to the first element in myCharArray
*myCharPointer; // first element
*(myCharPointer+3); // third element
myCharPointer - (myCharPointer + 3); // Should be 3, or 3 * sizeof(char)