Arrary dimension don't have to be const?

[northfly]

I cannot believe this, this dimension won't be known until runtime, but it works.

#include <iostream>
using namespace std;

int main() {
	int i;
	cin>>i;
	const int ci=i;
	int ai[ci];
	cin>>ai[0]>>ai[1];
	cout<<i<<endl;
	cout<<ai[0]<<ai[1];
	return 0;
}

why? who can explain this? a false pretended const also work?

[Cubbi]

No, this doesn't work: http://liveworkspace.org/code/5982d797a0e6a6fbcd93679b11ab9cad

Your compiler must be offering this functionality as a non-portable language extension.

[northfly]

really? I use GCC
and even if I input 1 for i, I can still input two values for ai[0], and ai[1] which should not be existing.

funny! I am confused!

[Cubbi]

With GCC, use -pedantic to make it report when it's using language extensions.

[northfly]

Thanks ,your information is very useful!