Difference between pointer and array in C?
Pointers are used for storing address of dynamically allocated arrays and for arrays which are passed as arguments to functions. In other contexts, arrays and pointer are two different things, see the following programs to justify this statement.
Behavior of sizeof operator
Size of arr 24 Size of ptr 8
Assigning any address to an array variable is not allowed.
Compiler Error: incompatible types when assigning to type 'int' from type 'int *'
See the previous post on this topic for more differences.
Although array and pointer are different things, following properties of array make them look similar.
- Array name gives address of first element of array.
Consider the following program for example.
Value of first element is 10
Array members are accessed using pointer arithmetic.
Compiler uses pointer arithmetic to access array element. For example, an expression like “arr[i]” is treated as *(arr + i) by the compiler. That is why the expressions like *(arr + i) work for array arr, and expressions like ptr[i] also work for pointer ptr.
arr = 30 *(arr + 2) = 30 ptr = 30 *(ptr + 2) = 30
Array parameters are always passed as pointers, even when we use square brackets.
sizeof(arr) = 24 sizeof(ptr) = 4 *ptr = 10
Let us see the differences in a tabular form -:
It is declared as -:
It is declared as -:
|2.||It is used to store the address of different variables of the same data type.||It is used to store the multiple variable of same data type|
|3.||We can generate a pointer to the array.||We can generate a array of pointer|
|4.||It is designed to store the address of variable||It is designed to store the value of variable.|
|5.||A pointer variable can store the address of only one variable at a time.||A array can store the number of elements the same size as the size of the array variable.|
Please refer Pointer vs Array in C for more details.
This article is contributed by Abhay Rathi. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above