Last element of an array is appearing different result in diff compilers

[Niranjanr]

#include <algorithm>
#include <cmath>
#include <cstdio>
#include <iostream>
#include <vector>
using namespace std;

int main() {

int n;
int a[n];
int numberOfSwaps = 0;
cin >> n;
for (int i = 0; i < n; i++) {
cin >> a[i];
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < n - 1; j++) {
if (a[j] > a[j + 1]) {
swap(a[j], a[j + 1]);
numberOfSwaps++;
}
}
}
for (int i = 0; i < n; i++) {
cout << a[i];
}

cout << "Array is sorted in " << numberOfSwaps <<" "<<"swaps"<<"\n";
cout << "First Element: " << a[0]<<"\n";
cout << "Last Element: " << a[n-1]<<"\n"; // This a[n-1] is acting weird with respect to compilers. any ideas why?

/* Enter your code here. Read input from STDIN. Print output to STDOUT
*/
return 0;
}

[dutch]

Edit your post and put your code in code tags.

This part is obviously wrong:

int n;
int a[n];   // what is the value of n when this statement is encountered? 

It looks like you meant:

int n;
cin >> n;
int a[n];

But even that is problematic since standard C++ doesn't have variable-length arrays. Instead, use a vector:

int n;
cin >> n;
vector<int> a(n);

[Niranjanr]

Yes, I understood where I went wrong

int n;
cin >> n;
int a[n];

This is the right way for my task.
thankyou

[dutch]

This is the right way for my task.

As long as you know that it isn't C++.

[salem c]

> Last element of an array is appearing different result in diff compilers

...

> This is the right way for my task.
You're still going to get different results on different compilers, but you just don't know it yet.