我對控制臺中的這種情況（下方）有疑問。
在創建 MyClass 物件后，在 main.ccp 中呼叫的我的方法中傳遞兩次后，資料會丟失。
主檔案
#include <QCoreApplication>
#include <QDebug>
#include <iostream>
#include <myclass.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
MyClass* myClass = new MyClass();
qDebug() << "Debug part 1";
myClass->method();
qDebug() << "Debug part 2";
myClass->method();
return a.exec();
}
控制臺中的結果：
Debug part 1
0
1 ".." "0 Bytes" "26.03.2022 08:21:13"
2 "stephane/" "0 Bytes" "26.04.2022 19:48:04"
3 ".localized" "0 Bytes" "26.03.2022 08:21:13"
4 "Shared/" "0 Bytes" "26.03.2022 08:21:13"
Debug part 2
0
源檔案：
myclass.h myclass.ccp entrys.h entry.ccp entry.h entry.ccp
我的班級.h
#ifndef MYCLASS_H
#define MYCLASS_H
#include <QObject>
#include <QString>
#include <QDateTime>
#include "entrys.h"
class MyClass : public QObject
{
Q_OBJECT
public:
explicit MyClass(QObject *parent = nullptr);
void method();
signals:
private:
Entrys* entrys;
};
#endif // MYCLASS_H
我的班級.ccp
#include "myclass.h"
#include <iostream>
#include "myclass.h"
#include "entry.h"
#include "entrys.h"
MyClass::MyClass(QObject *parent) : QObject(parent) {
this->entrys = new Entrys();
try {
this->entrys->setDir("/Users/","L");
} catch(ErrDirNotFound &e) {
qDebug() << e.description << " " << e.what();
}
}
void MyClass::method() {
int i = 0;
qDebug() << i;
foreach(Entry *v, this->entrys->getEntrys("L")) {
i ;
qDebug() << i << v->getName() << " " << v->getSizeString(2) << " " << v->getDateLastChangeString();
}
}
條目.h
#ifndef ENTRYS_H
#define ENTRYS_H
#include <QObject>
#include "entry.h"
struct ErrDirNotFound: public std::exception {
QString description;
const char *what() const throw() {
return "Directory not found";
}
};
class Entrys : public QObject
{
Q_OBJECT
public:
explicit Entrys(QObject *parent = nullptr);
void setDir(QString dir, QString side);
QVector<Entry*> getEntrys(QString side);
Entry* getEntry(QString side, QString key);
QString getPath(QString side);
protected:
signals:
private:
QHash<QString, QString> hash_path;
QHash<QString, QVector<Entry*>> hash_side_entry;
void setList(QString side);
};
#endif // ENTRYS_H
條目.ccp
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <QDebug>
#include <iostream>
#include <QDateTime>
#include <QProcess>
#include "entry.h"
#include "entrys.h"
Entrys::Entrys(QObject *parent)
: QObject{parent}
{
}
void Entrys::setList(QString side) {
QVector<Entry*> vec_entry;
QString path = this->getPath(side);
QByteArray path_ba = path.toLocal8Bit();
const char* path_cstr = path_ba.constData();
struct dirent *lecture;
DIR *dir;
struct stat buf;
QString currentPath;
int row = 0;
dir = opendir(path_cstr);
if (dir == NULL) {
ErrDirNotFound e;
QString description = "Path " path " don't exist !";
e.description = description;
throw e;
}
while ((lecture = readdir(dir)) != NULL) {
if (strcmp(lecture->d_name, ".") != 0) {
currentPath = path lecture->d_name;
QByteArray path_qb = currentPath.toLocal8Bit();
const char *charCurrentPath = path_qb.constData();
if ((stat(charCurrentPath, &buf)) == -1) {
qCritical() << "stat" << currentPath;
}
int size = buf.st_size;
QDateTime modif = QDateTime::fromSecsSinceEpoch(buf.st_mtime);
Entry *entry = new Entry();
if (!strcmp(lecture->d_name, "..")) {
if (this->getPath(side) != "/") {
entry->setValue(lecture->d_name, 0, modif, 0);
}
} else {
if (S_ISDIR(buf.st_mode)) {
QString qstringTemp = lecture->d_name;
qstringTemp = "/";
entry->setValue(qstringTemp, 0, modif, buf.st_mode);
} else {
entry->setValue(lecture->d_name, size, modif, buf.st_mode);
}
}
vec_entry.append(entry);
row ;
}
}
delete lecture;
closedir(dir);
this->hash_side_entry.insert(side, vec_entry);
}
void Entrys::setDir(QString dir, QString side) {
this->hash_path.insert(side, dir);
this->setList(side);
}
QVector<Entry*> Entrys::getEntrys(QString side) {
return this->hash_side_entry.take(side);
}
QString Entrys::getPath(QString side) {
return this->hash_path[side];
}
Entry* Entrys::getEntry(QString side, QString key) {
QVector<Entry*> entry = this->getEntrys(side);
for (int i = 0; i < entry.length(); i ) {
if (entry[i]->getName() == key) {
return entry[i];
}
}
return nullptr;
}
入口.h
#ifndef ENTRY_H
#define ENTRY_H
#include <QObject>
#include <QString>
#include <QDateTime>
class Entry : public QObject
{
Q_OBJECT
public:
explicit Entry(QObject *parent = nullptr);
Entry(QString name, int size_file, QDateTime date_last_change, mode_t mode);
void setValue(QString name, int size_file, QDateTime date_last_change, mode_t mode);
QString getName();
QString getSizeString(int decimals);
QString getDateLastChangeString();
signals:
private:
QString name;
int size_file;
QDateTime date_last_change;
mode_t mode;
};
#endif // ENTRY_H
入口.ccp
#include <QDateTime>
#include "entry.h"
Entry::Entry(QObject *parent)
: QObject{parent}
{
}
Entry::Entry(QString name, int size_file, QDateTime date_last_change, mode_t mode)
{
this->name = name;
this->size_file = size_file;
this->date_last_change = date_last_change;
this->mode = mode;
}
void Entry::setValue(QString name, int size_file, QDateTime date_last_change, mode_t mode)
{
this->name = name;
this->size_file = size_file;
this->date_last_change = date_last_change;
this->mode = mode;
}
QString Entry::getName()
{
return this->name;
}
QString Entry::getSizeString(int decimals) {
int bytes = this->size_file;
if (bytes == 0) return "0 Bytes";
const int K = 1024;
const QStringList SIZES = { "Bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
const int I = std::floor((std::log(bytes) / std::log(K)));
int dm = decimals < 0 ? 0 : decimals;
if (I == 0) dm = 0;
return QString::number((bytes / std::pow(K, I)),'f', dm) " " SIZES[I];
}
QString Entry::getDateLastChangeString() {
return this->date_last_change.toString("dd.MM.yyyy hh:mm:ss");
}
uj5u.com熱心網友回復：
通過眼睛跟蹤您的代碼，我發現這涉及：
QVector<Entry*> Entrys::getEntrys(QString side) {
return this->hash_side_entry.take(side);
}
一點谷歌搜索表明QHash“take從哈希中洗掉帶有鍵的專案并回傳與其關聯的值。” 所以你getEntrys正在修改你的hash_side_entry- 從中??取出資料。因此，當您的第二次呼叫method最終第二次呼叫getEntrys時，就沒有任何內容hash_side_entry了。
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