0 appears when outputting a shuffled array - c

Question

I've made a shuffling type program that obtains from cases[]; and arranges them in a random order.
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void deal(void);
int cases[22] = {1,2,3,4,5,6,8,10,15,20,25,35,50,65,85,100,105,135,165,200,250};
int main()
{
srand(time(NULL));
int a = 0;
deal();
for(a = 0 ; a < 22 ; a++)
printf("%d \n", cases[a]);
return 0;
}
void deal(void){
int loop;
int temp;
int x;
int y;
for(loop = 0; loop < 50; loop++){
x = rand() % 22;
y = rand() % 22;
temp = cases[x];
cases[x] = cases[y];
cases[y] = temp;
}
}
However when I run the code it comes with a randomly placed 0. Where is it from and why is it there?
Example output:
6
15
0 //I don't want that
20
5
50
10
3
165
65
135
105
8
1
200
25
100
85
2
250
4

Answer 1

You declared int cases[22] but initialized only 21 integers into that array and therefore, the last element will be 0 when not initialized. Try to add another integer at the end of the array

Answer 2

It's an off by one error: Ferico Samuel's answer is correct
This is a complement:
Instead of hard coding 22 as the number of cases you should write your program like this:
// no explicit declaration of the size here. The compiler automatically
// puts the correct size depending on the number of elements that follow.
int cases[] = {1,2,3,4,5,6,8,10,15,20,25,35,50,65,85,100,105,135,165,200,250};
...
for(a = 0 ; a < sizeof(cases) / sizeof(cases[0]); a++)
...
sizeof(cases) is the size of your cases array in bytes
sizeof(cases[0]) is the size of one element of the casesarray
thus sizeof(cases) / sizeof(cases[0])is the number of elements of the array.
This way you can add more elements to the cases array without the need to change the array size elsewhere in your program.

Answer 3

You declare your array as:
int cases[22] = {1,2,3,4,5,6,8,10,15,20,25,35,50,65,85,100,105,135,165,200,250};
Without you know it, there is actually only 21 elements in that array. Thus, in C standard compilers, the non-initialized value would be set as zero. To correct it, add one more element to the array.
int cases[22] = {1,2,3,4,5,6,8,10,15,20,25,35,50,65,85,100,105,135,165,200,250, 500}; // add 500
And things will be okay.
Anyway, for this kind of initialization, I recommend you to put the elements in multiple lines (say, every 10 elements):
int cases[22] = {1, 2, 3, 4, 5, 6, 8, 10, 15, 20,
25, 35, 50, 65, 85, 100,105,135,165,200,
250, 500}; // add 500
And put in nice format to avoid such error.

Answer 4

You have the wrong number of elements in the array. C is a bit stupid, because it is designed so that a compiler can only detect if there is too many elements in an array, but never if there is too few.
To ensure the exact amount of elements, you can declare arrays like this:
#define ARRAY_ITEMS(arr) (sizeof(arr) / sizeof(*arr))
#define CASES_ITEMS 22
int cases[] = {1,2,3,4,5,6,8,10,15,20,25,35,50,65,85,100,105,135,165,200,250};
_Static_assert(ARRAY_ITEMS(cases) == CASES_ITEMS, "Wrong array size: cases");