c ++使用前导零保存Int到String，不显示它们

Question

I can format an Int to display a number with leading zeros, but I can't figure out how to save an Int with the zeros to a string .

Reason: Loading image files that end in "..0001" "..0002" ... "..0059" etc.

I have this, but it doesn't work:

int a;
for(int i = 1; i < imgArraySize + 1; i++)
{
    cout << setw(4) << setfill('0') << i << '\n';
    cin >> a;
    string aValue = to_string(a);

    imageNames.push_back(string("test_images" + aValue + ".jpg"));
}

Answer 1

You can apply the same formatting with a stringstream

std::ostringstream ss;
ss << std::setw(4) << std::setfill('0') << a;
std::string str = ss.str();
std::cout << str;

Live example