I don't know why if how known pls tell me

Question

#include <stdio.h>

int main(){
int sam[3],i;
sam[1] = 5;
sam[2] = 5;
sam[3] = 6;
for (i=0;i<3;i++){
printf("%d\n",sam[i]);
}
}

(unexpected)the answer is
4200656
5
5
(expect)
5
5
6

Answer 1

An array is zero-index. So it start counting by 0.

int main()
{
int sam[3],i;
sam[0] = 5;
sam[1] = 5;
sam[2] = 6;
for (i=0;i<3;i++)
{
printf("%d\n",sam[i]);
}
}

you'll be fine

Answer 2

thank you so mush @sneeze