vector push_back after curly braces initializer does not work in C++

Asked Apr 16 '20 at 07:03

Active Apr 16 '20 at 07:03

Viewed 416 times

I have a vector with {} initializer. And then I use push_back to add an element into the vector. When I print the vector elements, the pushed element does not print. Why is that?

int main() {
    vector<int> vec = {0,1,2,3,4,5,6,7,8,9};
    vec.push_back(1);

    cout << "size = " << vec.size() << endl;

    cout << "vals: ";
    for (auto &v : vec) {
        cout << v << "\t" ;
    }
}

Output:

Value 1 should be printed, but it does not.

size = 11                                                                                                                                                                                                                                       
vals: 0 1       2       3       4       5       6       7       8       9

asked Apr 16 '20 at 07:03

Yun Li

2

Sounds like an output problem. Add a `cout << endl` after your for loop (to flush the buffer). – Timo Apr 16 '20 at 07:06
`cout` is unbufferred. – Jasper Kent Apr 16 '20 at 07:19
Works fine in Visual Studio 2019. What's your platform? What do you get *without* the `push_back`? – Jasper Kent Apr 16 '20 at 07:22
Works fine with ```cout << v << "\t" << endl;```, however ```cout << v << "\t" << flush;``` does not work. I am using this online compiler https://www.onlinegdb.com/ and choose C++17. – Yun Li Apr 16 '20 at 07:23
1

@YunLi look at the very right of the console. Somehow the tabs are broken there :D – Timo Apr 16 '20 at 07:29
Oh stupid me! Thanks! – Yun Li Apr 16 '20 at 07:30
@JasperKent `cout` is buffered but it is automatically flushed before a program ends. – Thomas Sablik Apr 16 '20 at 07:31
Regardless of flushing, C++ streams require a newline at the end of the output. Some systems won't show output without it; others will. `std::endl` writes a newline and does some other, usually unnecessary, stuff. – Pete Becker Apr 16 '20 at 15:57

vector push_back after curly braces initializer does not work in C++

0 Answers0