Thread: What's wrong with this (pointers)

Just starting off, trying to understand pointers. The basic idea is ok. I am wondering why you can't increment a pointer in a loop and hence assign the referenced variable a new value this way.

Such as,

Code:

#include <iostream>

using namespace std;

int main()
{
    int a; //int assigns 2 bytes of memory
    int *b; //declare pointer b 
    b = &a; //set b to address of a
    //*b= 0; //set dereference pointer(thus value of a = dereference value)
    for(int i =0; i<10; i++)
    {
        cout <<a<<"\n";
        *b++; //shouldn't this assigned a new value to a??
    }
    return 0;
}

If you say

Code:

int a=5;
int *b=&a
*b = 7

then a =7.

Thus a pointer allows you to both know the memory address of a variable(object) and also change that referenced variable through dereference.

So why doesn't the above loop change the value of a to increase by 1 each time?

Code:

    for(int i =0; i<10; i++)
    {
        cout <<a<<"\n";
        *b++; //shouldn't this assigned a new value to a??
    }

the post increment operater will be executed first -> first the pointer is incremented pointing to the next int in memory and that is dereferenced

you want (*b)++

Kurt