Length of array in C

This example program demonstrates how to get the length of a C array using the sizeof operator.

#include <stdio.h>

int int_array[5];

double double_array[10];

char char_array[] = {'a', 'b', 'c', 'd'};

int main ()
{
    const char * format = "The %s array has %d bytes and %d elements.\n";

    printf (format, "int",
            sizeof (int_array), sizeof (int_array) / sizeof (int));
    printf (format, "double",
            sizeof (double_array), sizeof (double_array) / sizeof (double));

    /* This method works even when the size of the array is not
       specified in the initializer. */

    printf (format, "char",
            sizeof (char_array), sizeof (char_array) / sizeof (char));
    return 0;
}

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It outputs the following:

The int array has 20 bytes and 5 elements.
The double array has 80 bytes and 10 elements.
The char array has 4 bytes and 4 elements.