Declaring global variable of <vector>, the code will can't run successfully

Question

This below is my code:

#include <iostream>
#include <vector>
using namespace std;

vector<int> vec;

int main() {
    cout << "Hello World!" << endl;
    return 0;
}

I use g++ to compile the code.It can be compiled successfully,but I can't see anything in CMD when I run the code.Then I delete the line:

vector<int> vec;

The code can print "Hello World!" in CMD.

Questions:

1. If we can't use global variable of vector?

2. Why the situation occurs?

Any help will be appreciated!

Answer 1

I ran this code on visual studio , gcc and on g++. Its result is hello world with or without "vector vec;".

please check it again..

Which command you are executing for compiling;

like this :- g++ program_name -o any_name

or something else.