Checking if a folder exists (and creating folders)

问题:

In Qt, how do I check if a given folder exists in the current directory?
If it doesn't exist, how do I then create an empty folder?

回答1:

To check if a directory named "Folder" exists use:

QDir("Folder").exists();

To create a new folder named "MyFolder" use:

QDir().mkdir("MyFolder");

回答2:

To both check if it exists and create if it doesn't, including intermediaries:

QDir dir("path/to/dir");
if (!dir.exists())
    dir.mkpath(".");

回答3:

When you use QDir.mkpath() it returns true if the path already exists, in the other hand QDir.mkdir() returns false if the path already exists. So depending on your program you have to choose which fits better.

You can see more on Qt Documentation

回答4:

If you need an empty folder you can loop until you get an empty folder

    QString folder= QString ("%1").arg(QDateTime::currentMSecsSinceEpoch());
    while(QDir(folder).exists())
    {
         folder= QString ("%1").arg(QDateTime::currentMSecsSinceEpoch());
    }
    QDir().mkdir(folder);

This case you will get a folder name with a number .

回答5:

Why use anything else?

  mkdir(...);