Are Arrays Pointers in C and C ?

Contrary to intuitive assumptions, arrays are distinct entities from pointers in both C and C . Let's delve into their differences.

Expression Conversion

In C and C , array expressions undergo type conversion to pointers under certain circumstances. When an array expression is not used as an operand of "&" (address-of operator), "sizeof" (size operator), or as a string literal initializing another array, its type transforms into a pointer to its initial element.

Memory Layout

Arrays occupy contiguous memory locations where their elements are stored sequentially. In contrast, pointers store the address of a single memory location.

Type Considerations

The types of array expressions differ from pointer types. For instance, the expression "arr" of an array "arr" has the type "pointer to type," while "&arr" has the type "pointer to pointer to type."

Pointer Arithmetic

Pointer arithmetic allows incrementing or decrementing pointers to navigate memory. When applied to an array expression, pointer arithmetic is effectively performed on its converted pointer value. This allows the use of the subscript operator "[" on both arrays and pointers, making it appear as though they were interchangeable for this operation.

Example

Consider the following code snippet:

int arr[10] = {0,1,2,3,4,5,6,7,8,9};
int *ptr = arr;
*ptr += 2;
printf("arr[2]: %d\n", arr[2]);

In this example, the array expression "arr" converts to a pointer, and incrementing this pointer moves it to point to the third element in the array. As a result, "arr[2]" still accesses the same third element.

In conclusion, arrays and pointers in C and C are separate entities, though array expressions undergo specific type conversion rules that allow them to behave like pointers in certain contexts. Their distinct types, memory layout, and pointer arithmetic properties differentiate them fundamentally.

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