C Program output differs on different machines - c

Question

I have the following program -
#include <stdio.h>
int main() {
int counter = 0;
int responses[28];
printf("Enter student section values: \n");
while(counter != 27) {
scanf("%d", &responses[counter]);
counter++;
}
int i = 0;
int arrayBlank[100];
int temp = 0;
int past = 0;
int present = 0;
int future = 0;
int flag = 0;
for(i = 0; i < counter; i++) {
if((i - 1) < 0 || (i + 1 >= counter)) {
;
}
else {
past = responses[i - 1];
present = responses[i];
future = responses[i + 1];
if(present == past || present == future) {
temp = present;
flag=1;
arrayBlank[temp]++;
} else {
arrayBlank[i] = 0;
}
}
}
if(flag == 0) {
printf("\nThe order input does not assign any adjacent students from the same team\n");
return 0;
} else {
int chut[28];
int index = 0;
for(i = 0; i < 27; i++) {
index = responses[i];
chut[index]++;
}
for(i = 0; i < 27; i++) {
if(chut[i] <= 0 || chut[i] > 26) {
chut[i] = 0;
}
}
printf("\nThe order input currently assigns adjacent students from the same team.\n");
printf("\nTeam Students\n");
for(i = 0; i < 27; i++) {
if(chut[i] != 0) {
printf("%d %d\n", i, chut[i]);
}
}
//1 2 3 3 4 5 6 7 8 9 1 2 3 4 5 5 7 8 9 1 2 3 4 5 6 7 8 8
}
return 0;
}
Basically for a given range of numbers, it checks if there is any particular number in the given entries that has an adjacent value which is the same as that number. If there is, it will just print how many times a particular element appeared in the given range of numbers.
Example - For a list of numbers
1 2 3 3 4 5 6 7 8 9 1 2 3 4 5 5 7 8 9 1 2 3 4 5 6 7 8 8
The program execution would be like -
Enter student section values: 1 2 3 3 5 6 7 8 9 1 2 3 4 5 5 7 8 9 1 2 3 4 5 6 7 8 8
The order input currently assigns adjacent students from the same team.
Team Students
1 3
2 3
3 4
4 2
5 4
6 2
7 3
8 4
9 2
Issue : I am not able to figure out the reason why the output is different on different machines and how I could fix that. For example, the output is correct on my Macbook running the program with XCode although it is different when I run it on a Linux machine with gcc compiler (Big Endian machine). I am not sure if the Endianess has anything to do with the outputs being different though.
On a Little Endian Linux machine -
On a Big Endian Linux machine -
On an online compiler (Tutorial's Point) -

Answer 1

The main problem, as far as I can see, is that you haven't initialized arrayBlank and are using it in:
arrayBlank[temp]++;
That certainly is cause for undefined behavior. I would initialize arrayBlank to zero using
int arrayBlank[100] = {0};
The secondary problem is that the loop counter to read the data is not right. Instead of:
while(counter != 27) {
scanf("%d", &responses[counter]);
use:
while(counter != 28) {
scanf("%d", &responses[counter]);
When you use counter != 27 to stop, the last element of responses, which can be accessed using index 27 is never read from file.