Expression must be a modifiable lvalue

Question

Hello,

The below code doesn't work.

# include <stdio.h>
int main()
{
    int arr[] = { 12,14,15,23,45 };

    for (size_t i = 0; i < 5; i++)
    {
        printf("%d\t",*arr);
        arr++;
    }

    return 0;
}

But the following code work.
I just saved arr in another variable.
Why the arr variable itself doesn't work?
We should be saved arr in another variable then we could use it.

# include <stdio.h>
int main()
{
    int arr[] = { 12,14,15,23,45 };
    int* a = arr;
    for (size_t i = 0; i < 5; i++)
    {

        printf("%d\t", *a);
        a++;
    }

    return 0;
}

Answer 1

arr++ is attempting to increment the array. You can't do that.
The fact that the name of an array can be used like a pointer
to access an array does not mean that the name of the array is
a pointer. It "decays" - is translated into by the compiler - a
pointer, in some contexts.

You appear to be struggling with the concepts of arrays and pointers, as
used in the C language (and inherited by C++). I strongly suggest that
you spend as much time as needed to study the available tutorials and
documentation on pointers and arrays, Otherwise you will be coming back
to these forums repeatedly asking why your code doesn't work as expected.

A TUTORIAL ON POINTERS AND ARRAYS IN C
https://pdos.csail.mit.edu/6.828/2014/readings/pointers.pdf

Relationship Between Arrays and Pointers
https://www.programiz.com/c-programming/c-pointers-arrays

6.8 — Pointers and arrays
https://www.learncpp.com/cpp-tutorial/6-8-pointers-and-arrays/

Exceptions to array decaying into a pointer?
https://stackoverflow.com/questions/17752978/exceptions-to-array-decaying-into-a-pointer

Pointer to an Array in C
https://www.tutorialspoint.com/cprogramming/c_pointer_to_an_array.htm

6. Arrays and Pointers
http://c-faq.com/aryptr/index.html

comp.lang.c FAQ list · Question 6.12
http://c-faq.com/aryptr/aryvsadr.html

comp.lang.c FAQ list · Question 6.13
http://c-faq.com/aryptr/ptrtoarray.html

• Wayne