C how do I check if an array is full? - c

Question

I have an array: array[3][3]
I will let the user input data into the array as long as it is not full. As soon as the array gets full I want to stop the user from inserting more data into it.

Answer 1

C has no array bounds check. You have to do it yourself. Use a variable to keep track of how many items you have inserted, and stop when your counter is equal to the array size.

Answer 2

You cannot check if "array is full". To do what u want to do, keep track of index while adding elements to array.

Answer 3

You need to keep track of the data inserted by a user. When your counter reaches the size of the array, the array is full. :D There is not other way in C to achieve this result as it does not provide any means of verifying how many elements are in the array.

Answer 4

Introduce a variable for counting the number of cells filled. You adjust this variable whenever you add/remove data to your array. Then, in order to check if your array is full, just check if this variable is equal to the total number of cells in your array.

Answer 5

The most simple way in my opinion is to dynamically allocate memory using calloc(), where you can initialise the array elements to, for example, zeros. The you can check if the array is full by checking, if the last element in the array is still zero or not. Of course, if the last element is still zero, then the array is not full.

Answer 6

First of all this is not an array but a matrix (aka array of array). you already know that the matrix has dimensions 3x3 and then you could do something like this:
int x, y;
int array[3][3];
for (x = 0; x<2; x++)
{
for (y = 0; y<2; y++)
{
//I assume that it is an array of int
printf("Insert number at %d - %d" ,x,y);
scanf("%d" ,&array[x][y]);
}
}
Now the user can only insert 3*3=9 values.

Answer 7

There are no way to array bound check in C, However with better coding practice we check whether array is full.
For example, consider in your array a[3][3] you don't want to have some particular value. That value could be anything! 0xFF or 0 or anything which is in the integer range! and you have to make sure that value is never given as the input to the array, and then you can verify whether your array a[3][3] is full!
/*part of coed in main*/
/*here initialize the array with 0, assuming that 0 will never be a part of array a[3][3]*/
for(i=0; i<3; i++)
{
for(j=0;j<3;j++)
{
a[i][j] = 0; // assuming that 0 will never be a part of array a[3][3]
}
}
while(CheckArray(**a)!=0)
{
printf("give array input:\n")
scanf("%d", &a[row][column]); //writing to empty cell of an array
}
//CheckArray code
int CheckArray(int a[][])
{
for(i=0; i<3; i++)
{
for(j=0;j<3;j++)
{
if(a[i][j] == 0) // assuming that 0 will never be a part of array a[3][3]
{
row = i; // row and column must be global variables in this example!
column = j; // row and column must be global variables in this example!
return 1;
}
else
{
// no need to do anything here
}
}
}
//if code reaches here then array is full!
printf("Array is full.\n");
return 0;
}
You can still optimize the above code! this is just one way of checking whether array is full with better coding practice!

Answer 8

If possible, you could initialize all elements in the array to a certain value that your program would otherwise consider "illegal" or "invalid". E.g. an array of positive numbers can be initialized to be all -1's. Or an array of chars can be initialized to be all NULL characters.
Then, just look at the last element if it is set to the default value.
measurement = sizeof(myarray) / sizeof(element); //or just a constant
while(myarray[measurement-1] == defaultvalue){
//insert code here...
}

Answer 9

Encapsulate the behavior into a struct with getter/setter functions that check for the max length of the desired vector:
typedef varvector
varvector;
struct varvector {
int length;
void* vector;
};
varvector* varvector_create(int length) {
varvector* container = malloc(sizeof(varvector));
void* vector = malloc(length);
if(container && vector) {
container->vector = vector;
}
return(container);
}
void varvector_destroy(varvector* container) {
free(container.vector);
free(container);
}
varvector_get(varvector* container, int position) {
if(position < container.length) {
return(container->vector[position]);
}
}
varvector_set(varvector* container, int position, char value) {
if(position < container.length) {
container->vector[position] = value
}
}
Object Oriented Programming is a design pattern which happens to have syntactic support in some languages and happens to not have syntactic support in C.
This does not mean that you cannot use this design pattern in your work, it just means you have to either use a library that already provides this for you (glib, ooc) or if you only need a small subset of these features, write your own basic functions.

Answer 10

You can assume that the last element of an array has id=0.
Then in function add check if there is an element with id=0.
int add(char *source, char *target, int size) {
int index = 0;
for (int i = 0; i < size; i++) {
if (target[i].id == 0) {
index = i;
break;
}
}
if (index >= 0 && index < size) {
if (index < size - 1) target[index + 1].id = 0;
// check that element with id=0 is the last in the array
//write code to add your element here
return index;
}
}