CODEWITHSUNDEEP
carrayscount
H. M. MOHIDUL ISLAM SHOVON
H. M. MOHIDUL ISLAM SHOVON

Reputation: 99

How to count number of element in an int type array where 0 can be an element?

Expectation: I want to count number of element available in an int type of array where 0 can be an element.

Following program output:

Total Element :6

Expected output:

Total Element :9

The code:

#include <stdio.h>

int main() {

    int a[50] = { 1, 2, -3, 0, 0, 6, 7, -8, 0 };
    int count = 0;

    int i = 0;
    for (i = 0; i < 50; i++) {
        if (a[i]) {
            count++;
        }
    }
    printf("Total Element :%d ", count);

    return 0;
}

NB: I want to count the total number of elements in the array. I do not want to count the size of the array.

Upvotes: 3

Views: 524

Answers (3)

the kamilz
the kamilz

Reputation: 1988

Use a sentinel value, i.e. choose a magic number (like 0xDEADBEEF).

and change your code like this:

#define SENTINEL 0xDEADBEEF

int main() {
    int a[50] = { 1, 2, -3, 0, 0, 6, 7, -8, 0, SENTINEL };
    int count = 0;

    int i = 0;
    for (i = 0; i < 50; i++) {
        if (a[i] == SENTINEL)
            break;
        if (a[i]) {
            count++;
        }
    }

    printf("Total Element :%d ", count);
    return 0;
}

Hope that helps.

Upvotes: 1

alk
alk

Reputation: 70951

I want to count Total number of element in array

As it stands, you cannot.

In C an array does not know which elements ever had been used or not.

If it is not possible to define a sentinel, a stopper-value, but you know the initialiser you could do the following:

#include <stddef.h> /* for size_t */
#include <stdio.h>

#define ARRAY_INITIALISER {1, 2, -3, 0, 0, 6, 7, -8, 0}


int main()
{
    int a[50] = ARRAY_INITIALISER;
    size_t count;

    {
      int tmp[] = ARRAY_INITIALISER;

      count = sizeof tmp / sizeof *tmp;
    }

    printf("Total number of elements 'used': %zu\n", count);

    return 0;
}

Upvotes: 4

M Oehm
M Oehm

Reputation: 29126

If you want to have a fixed buffer of 50 elements, but the "active" array can have any length and you have no valid sentinel element (such as the null character in strings, or may eb a NULL pointer or 0 or −1 or INT_MIN in integer arrays), you must keep track of the active length count from the start:

int a[50] = {1, 2, -3, 0, 0, 6, 7, -8, 0};
int count = 9;

If you want to build the array dynamically, start with an ampty array and a zero count, then "push" the elements to the array:

int a[50];
int count = 0;

a[count++] = 1;
a[count++] = 2;
a[count++] = -3;
a[count++] = 0;

Take care not to overflow the underlying fixed-size array.

Upvotes: 1

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