Qdir的函数exists（）始终返回true，即使该目录不存在

Question

我试图在指定的基本目录中创建一个文件夹的项目的第一部分进行防错。基本目录由用户在QLineEdit中手动选择，或者使用QFileDialog浏览计算机的目录。我想，如果存在的基本目录之前，我使用下面的命令使一个子文件夹中它来检查：

QString base_dir = ui->baseDir->text(); 
QString blank = ""; 
QString no_text1 = "Please enter a valid directory"; 
if(base_dir==no_text1 || base_dir==blank) { 
    if(!QDir(base_dir).exists()) {   //does base directory exist? 
    ui->baseDir->setText(no_text1); 
    return; 
    } 
} 

的问题是，我是否键入一个有效的目录进行编辑，或无效一个（即随机短语）第二个if语句总是返回false，意味着exists（）总是返回true。第一条if语句正常工作。我只是使用exists（）错误？

编辑： 完整的代码

#include "mainwindow.h" 
#include "ui_mainwindow.h" 
#include "functions.h" 
#include <QtGui/QApplication> 
#include <QFileDialog> 
#include <fstream> 

MainWindow::MainWindow(QWidget *parent) : 
    QMainWindow(parent), 
    ui(new Ui::MainWindow) 
{ 
    ui->setupUi(this); 
} 

MainWindow::~MainWindow() 
{ 
    delete ui; 
} 




// This is the function that handles the directory search when the 'browse' button is pressed 
void MainWindow::on_findDir_clicked() 
{ 
    QString path; //declaring the path to the base directory 

    path = QFileDialog::getExistingDirectory( //gathering the directory from QFileDialog class 
     this, tr("Choose the project directory"), 
     "/home", 
     QFileDialog::ShowDirsOnly 
     | QFileDialog::DontResolveSymlinks); 

    ui->baseDir->setText(path); //setting the retrieved path into the line edit box 
} 



// This function makes the project by creating a new directory with name 'project_name' 
// in the base directory, and collects the OpenFOAM version number and simulation type 
void MainWindow::on_create_clicked() 
{ 

    QString project_name, foam_version, full_dir, slash, base_dir; 
    base_dir = ui->baseDir->text(); 
    project_name = ui->projectName->text();  //getting the text from the 'projectName' field 
    foam_version = ui->version->currentText(); //getting the selection from the 'version' drop-down box 

    //first checking if the fields have input in them: 
    QString blank = ""; 
    QString no_text0 = "Please enter project name"; 
    if(project_name==no_text0 || (project_name==blank)) { 
     ui->projectName->setText(no_text0); 
     return; 
    } 


    QString no_text1 = "Please enter a valid directory"; 
    if(base_dir==no_text1 || base_dir==blank) { 
     if(!QDir(base_dir).exists()) {   //does base directory exist? 
     ui->baseDir->setText(no_text1); 
     return; 
     } 
    } 


    slash = "/";  // needed to separate folders in the directory (can't use a literal) 
    full_dir = base_dir.append(slash.append(project_name)); 

    if(!QDir(full_dir).exists()) //check if directory already exists 
     QDir().mkdir(full_dir);  //creating directory 

    QString blockmesh_filename, suffix; 
    suffix = "_blockmesh"; 
    slash = "/"; //must re-define 
    blockmesh_filename = full_dir.append(slash.append(project_name.append(suffix))); 
    std::ofstream create_file(blockmesh_filename.toStdString().c_str()); //creating empty blockmesh file 

} 

Answer 1

你的第二个如果，如果你在文本字段中键入任何声明将不会被执行。你的逻辑在第一个if语句中表示如果输入是空的或预定义的字符串，则测试是否存在dir。这意味着你总是使用空字符串或罐头消息进行测试。

正确的逻辑应该是：

if(base_dir!=no_text1 && base_dir!=blank) { 
    ....