Yes. The array name is a reference to the array, so you can use sizeof (name) / sizeof (name[0]) to determine the number of elements. Note that sizeof (name) alone gives the length of the array in bytes.
element_address = array_address + (element_index * element_size) Note that the array name refers to the start address of the array, element indices are always zero-based and element size is calculated at compile time using the sizeof() operator using the array type as the operand. int x[10]; int* p1 = x + (5 * sizeof(int)); // calculate address of 6th element int* p2 = &x[5]; // return address of 6th element assert (p1==p2); // ensure both address are equal Note that the array suffix operator [] used by p2 is merely sugar-coating. Behind the scenes, the compiler will automatically generate code equivalent to that of the p1 calculation. As such, there is no advantage in using one over the other.
#include <stdlib.h> int **array1 = malloc(nrows * sizeof(int *)); for(i = 0; i < nrows; i++) array1[i] = malloc(ncolumns * sizeof(int));
printf ("sizeof (int) = %d\n", (int)sizeof (int));
There is no "NULL array" as such, you may take a pointer to an array and set it to NULL (binary 0) e.g. int* foo; // Declare a pointer foo = malloc( 40 * sizeof(int)); //Allocate an array of 40 integers pointed to by "foo" foo = NULL; //Set the pointer to NULL, if you're using a garbage collector this should trigger an automatic free() of the memory allocated to the array. If you are NOT using a garbage collector (which is more common in C) this line is a memory leak.
An array's name implicitly converts to a pointer to the first element of the array at the slightest provocation. Thus to access the first element of the array, the array name suffices. To access any other element in the array without using the suffix operator, use offset pointer arithmetic. For example: int a[] = {2, 4, 6, 8, 10}; int b; b = *(a+3); assert (b == 8); Here, (a+3) points to the 4th element (offset 3). Dereferencing this address returns the value of that element, in this case 8.
element_address = array_address + (element_index * element_size) Note that the array name refers to the start address of the array, element indices are always zero-based and element size is calculated at compile time using the sizeof() operator using the array type as the operand. int x[10]; int* p1 = x + (5 * sizeof(int)); // calculate address of 6th element int* p2 = &x[5]; // return address of 6th element assert (p1==p2); // ensure both address are equal Note that the array suffix operator [] used by p2 is merely sugar-coating. Behind the scenes, the compiler will automatically generate code equivalent to that of the p1 calculation. As such, there is no advantage in using one over the other.
#include <stdlib.h> int **array1 = malloc(nrows * sizeof(int *)); for(i = 0; i < nrows; i++) array1[i] = malloc(ncolumns * sizeof(int));
YourType *p; p = (YourType *)calloc (no_of_elements, sizeof (YourType)); if (p==NULL) { fprintf (stderr, "Out of memory\n"); exit (32); }
printf ("sizeof (int) = %d\n", (int)sizeof (int));
There is no "NULL array" as such, you may take a pointer to an array and set it to NULL (binary 0) e.g. int* foo; // Declare a pointer foo = malloc( 40 * sizeof(int)); //Allocate an array of 40 integers pointed to by "foo" foo = NULL; //Set the pointer to NULL, if you're using a garbage collector this should trigger an automatic free() of the memory allocated to the array. If you are NOT using a garbage collector (which is more common in C) this line is a memory leak.
An array's name implicitly converts to a pointer to the first element of the array at the slightest provocation. Thus to access the first element of the array, the array name suffices. To access any other element in the array without using the suffix operator, use offset pointer arithmetic. For example: int a[] = {2, 4, 6, 8, 10}; int b; b = *(a+3); assert (b == 8); Here, (a+3) points to the 4th element (offset 3). Dereferencing this address returns the value of that element, in this case 8.
An array is an aggregate of elements, where memory is allocated to accommodate a given number of elements of a given type. The name of the array serves as a reference to the first element of the array. Unlike ordinary (non-array) variables, all the other elements of an array have no name; they are anonymous. However, all elements of an array have identity (they have an address) so if we know the address of an element within an array we can easily refer to it by that address. Given that each element is of the same type and therefore the same size (in bytes), we can easily calculate the address of each element offset from the start of the array. That is, the nth element of an array A of type T will be found at address A + sizeof(T) * (n-1). Although we are free to use "pointer arithmetic" like this to calculate the individual addresses of each element, C provides us with a much more convenient notation called the array suffix operator. The array suffix operator applies to pointer variables only. Fortunately, all arrays implicitly convert to a pointer at the slightest provocation so we don't have to do anything special to use them. The operator is denoted using square brackets [] such that for an array A we can refer to its nth element as A[n-1]. Given that A is of type T, the compiler has enough information to generate the required pointer arithmetic for us: A + sizeof(T) * (n-1). Note that array indices are in the range 0 to n-1 for an array of n elements. Attempting to access elements outwith this range has undefined behaviour, so it is important that we take steps to ensure all indices are kept within the bounds of the array. For fixed-length arrays, we can simply use a constant to store the array length, but for variable-length arrays we must keep track of the length using a variable. To range-check a given index against a given length, n, the index must be in the closed range [0:n-1]. However, array index ranges are often denoted using half-closed notation, [0:n), which essentially means 0 <= index < n.
Pointer is a variable that stores the address of another variable . So pointer basically stores the address of another variable and size of pointer can be evaluated by using sizeof operator.
Use the array suffix operator ([]), or use a pointer offset from the start of the array, such that an offset of 1 is equivalent to the size of an array element (all elements in an array must be of equal size). The latter method is what actually goes on behind the scenes when using the array suffix operator, but the former is generally easier to use.
The number of dimensions is immaterial. All arrays are implemented as a one dimensional array. A multidimensional array is simply an array where every element is itself an array. The only thing actually known about any array is that its name is a reference to the start address. Unlike an ordinary (non-array) variable, the elements in the array do not have names, we can only refer to them by their memory offsets from the start of the array. As such, in order to obtain the values stored at those offsets, we must dereference them. While the subscript operator gives us notational convenience, it's easy to forget that there's actually pointer arithmetic and dereferencing going on behind the scenes.
using sizeof operator the size of whole array can be calculated, then divide it with the zise of the datatype(E.g. for int =4, char =2....etc.) Example: #define Narray (sizeof(array)/sizeof(array[0]))
implement the queue ADT using an array