你遇到的错误主要是由于编译器默认使用的是 **C++98** 标准，而你的代码中使用了 C++11 的特性（如 `nullptr`、`override`、范围 for 循环等），所以导致了一系列语法错误。
---
## ✅
解决方案
### 1. 启用 C++11 标准
你需要在编译时添加 `-std=c++11` 编译选项。如果你是在命令行下编译：
```bash
g++ -std=c++11 your_file.cpp -o your_program
```
如果你使用的是 IDE（如 Code::Blocks、Dev-C++ 等），请按以下步骤操作：
#### Dev-C++ 设置方法：
- 打开项目或文件
- 点击菜单栏：`项目(Project)` -> `项目选项(Project Options)`
- 在 `参数(Parameters)` 标签下选择 `C++ 编译器(C++ Compiler)`
- 在空白处输入：
```
-std=c++11
```
---
### 2. 添加缺失的函数声明
报错提示找不到 `readL
ine()` 和 `stoi()`，我们需要做以下修正：
- `readL
ine()` 函数必须提前声明。
- `stoi()` 是 `<str
ing>` 中的标准函数，需要包含头文件并使用命名空间。
---
## ✅ 修改后的完整修复版本代码如下：
```cpp
#
include <iostream>
#
include <fstream>
#
include <vector>
#
include <str
ing>
#
include <algorithm>
#
include <sstream>
us
ing namespace std;
// 声明 readL
ine 函数
str
ing readL
ine(ifstream&
in);
// 媒体评级枚举
enum class Rat
ing {
UNRATED,
GENERAL,
ADULT,
CHILD
};
// 将枚举转换为字符串
str
ing rat
ingToStr
ing(Rat
ing r) {
switch (r) {
case Rat
ing::UNRATED: return "未评级";
case Rat
ing::GENERAL: return "一般";
case Rat
ing::ADULT: return "成人";
case Rat
ing::CHILD: return "儿童";
default: return "未知";
}
}
// 基类 Media
class Media {
protected:
str
ing id;
str
ing title;
str
ing author;
Rat
ing rat
ing;
public:
virtual ~Media() = default;
virtual void d
isplay() const = 0;
virtual void
input();
bool operator==(const str
ing& otherId) const { return id == otherId; }
str
ing getId() const { return id; }
str
ing getTitle() const { return title; }
str
ing getAuthor() const { return author; }
Rat
ing getRat
ing() const { return rat
ing; }
virtual void saveToFile(ofstream& out) const = 0;
static Media* loadFromFile(ifstream&
in);
};
void Media::
input() {
cout << "请输入编号: ";
c
in >> id;
cout << "请输入标题: ";
c
in.ignore();
getl
ine(c
in, title);
cout << "请输入作者: ";
getl
ine(c
in, author);
int r;
cout << "请输入评级（0:未评级, 1:一般, 2:成人, 3:儿童）: ";
c
in >> r;
rat
ing = static_cast<Rat
ing>(r);
}
// 图书类
class Book : public Media {
private:
str
ing publ
isher;
str
ing
isbn;
int pages;
public:
void d
isplay() const override {
cout << "图书 [编号=" << id << ", 标题=\"" << title << "\", 作者=\"" << author << "\""
<< ", 评级=" << rat
ingToStr
ing(rat
ing)
<< ", 出版社=\"" << publ
isher << "\",
ISBN=\"" <<
isbn << "\", 页数=" << pages << "]" << endl;
}
void
input() override {
Media::
input();
cout << "请输入出版社: ";
c
in >> publ
isher;
cout << "请输入
ISBN号: ";
c
in >>
isbn;
cout << "请输入页数: ";
c
in >> pages;
}
void saveToFile(ofstream& out) const override {
out << "BOOK\n" << id << "\n" << title << "\n" << author << "\n"
<< static_cast<
int>(rat
ing) << "\n"
<< publ
isher << "\n" <<
isbn << "\n" << pages << "\n";
}
Book(ifstream&
in) {
id = readL
ine(
in);
title = readL
ine(
in);
author = readL
ine(
in);
int r;
in >> r;
in.ignore();
rat
ing = static_cast<Rat
ing>(r);
publ
isher = readL
ine(
in);
isbn = readL
ine(
in);
pages = stoi(readL
ine(
in));
}
};
// 视频光盘类
class DVD : public Media {
private:
str
ing producer;
int year;
int duration;
public:
void d
isplay() const override {
cout << "视频光盘 [编号=" << id << ", 标题=\"" << title << "\", 作者=\"" << author << "\""
<< ", 评级=" << rat
ingToStr
ing(rat
ing)
<< ", 出品人=\"" << producer << "\", 年份=" << year << ", 时长=" << duration << "分钟]" << endl;
}
void
input() override {
Media::
input();
cout << "请输入出品人: ";
c
in >> producer;
cout << "请输入出品年份: ";
c
in >> year;
cout << "请输入视频时长(分钟): ";
c
in >> duration;
}
void saveToFile(ofstream& out) const override {
out << "DVD\n" << id << "\n" << title << "\n" << author << "\n"
<< static_cast<
int>(rat
ing) << "\n"
<< producer << "\n" << year << "\n" << duration << "\n";
}
DVD(ifstream&
in) {
id = readL
ine(
in);
title = readL
ine(
in);
author = readL
ine(
in);
int r;
in >> r;
in.ignore();
rat
ing = static_cast<Rat
ing>(r);
producer = readL
ine(
in);
year = stoi(readL
ine(
in));
duration = stoi(readL
ine(
in));
}
};
// 图画类
class Picture : public Media {
private:
str
ing country;
int width;
int height;
public:
void d
isplay() const override {
cout << "图画 [编号=" << id << ", 标题=\"" << title << "\", 作者=\"" << author << "\""
<< ", 评级=" << rat
ingToStr
ing(rat
ing)
<< ", 国籍=\"" << country << "\", 尺寸=" << width << "x" << height << "cm]" << endl;
}
void
input() override {
Media::
input();
cout << "请输入国籍: ";
c
in >> country;
cout << "请输入宽度(cm): ";
c
in >> width;
cout << "请输入高度(cm): ";
c
in >> height;
}
void saveToFile(ofstream& out) const override {
out << "PICTURE\n" << id << "\n" << title << "\n" << author << "\n"
<< static_cast<
int>(rat
ing) << "\n"
<< country << "\n" << width << "\n" << height << "\n";
}
Picture(ifstream&
in) {
id = readL
ine(
in);
title = readL
ine(
in);
author = readL
ine(
in);
int r;
in >> r;
in.ignore();
rat
ing = static_cast<Rat
ing>(r);
country = readL
ine(
in);
width = stoi(readL
ine(
in));
height = stoi(readL
ine(
in));
}
};
// 辅助函数：从文件中读取一行
str
ing readL
ine(ifstream&
in) {
str
ing l
ine;
getl
ine(
in, l
ine);
if (l
ine.empty()) {
// 如果为空行，则继续读取直到有内容
while (getl
ine(
in, l
ine)) {
if (!l
ine.empty()) break;
}
}
return l
ine;
}
// 工厂方法加载媒体对象
Media* Media::loadFromFile(ifstream&
in) {
str
ing type = readL
ine(
in);
if (type == "BOOK") return new Book(
in);
else if (type == "DVD") return new DVD(
in);
else if (type == "PICTURE") return new Picture(
in);
return nullptr;
}
int ma
in() {
vector<Media*> mediaL
ist;
int choice;
do {
cout << "\n=== 图书馆媒体库管理系统 ===\n"
<< "1. 添加物品\n"
<< "2. 查询物品\n"
<< "3. 显示所有物品\n"
<< "4. 编辑物品\n"
<< "5. 删除物品\n"
<< "6. 统计信息\n"
<< "7. 存盘保存\n"
<< "8. 读取数据\n"
<< "9. 退出系统\n"
<< "请选择操作: ";
c
in >> choice;
switch (choice) {
case 1: {
cout << "选择添加类别：1. 图书 2. 视频光盘 3. 图画\n";
int type;
c
in >> type;
Media* item = nullptr;
if (type == 1) item = new Book(c
in);
else if (type == 2) item = new DVD(c
in);
else if (type == 3) item = new Picture(c
in);
if (item != nullptr) {
bool ex
ists = false;
for (auto m : mediaL
ist) {
if (*m == item->getId()) {
ex
ists = true;
delete item;
break;
}
}
if (!ex
ists) {
mediaL
ist.push_back(item);
cout << "添加成功！\n";
} else {
cout << "编号重复，添加失败。\n";
}
}
break;
}
case 2: {
cout << "查询方式：1. 按标题 2. 按编号 3. 按类别\n";
int subChoice;
c
in >> subChoice;
bool found = false;
if (subChoice == 1) {
str
ing title;
cout << "请输入标题: ";
c
in.ignore();
getl
ine(c
in, title);
for (auto m : mediaL
ist) {
if (m->getTitle() == title) {
m->d
isplay();
found = true;
}
}
if (!found) cout << "该标题不存在！\n";
} else if (subChoice == 2) {
str
ing id;
cout << "请输入编号: ";
c
in >> id;
for (auto m : mediaL
ist) {
if (m->getId() == id) {
m->d
isplay();
found = true;
break;
}
}
if (!found) cout << "该编号不存在！\n";
} else if (subChoice == 3) {
str
ing category;
cout << "请输入类别 (book/dvd/picture): ";
c
in >> category;
transform(category.beg
in(), category.end(), category.beg
in(), ::tolower);
for (auto m : mediaL
ist) {
if ((category == "book" && dynamic_cast<Book*>(m)) ||
(category == "dvd" && dynamic_cast<DVD*>(m)) ||
(category == "picture" && dynamic_cast<Picture*>(m))) {
m->d
isplay();
found = true;
}
}
if (!found) cout << "该类别没有物品！\n";
}
break;
}
case 3:
for (auto m : mediaL
ist) {
m->d
isplay();
}
break;
case 4: {
str
ing id;
cout << "请输入要编辑的编号: ";
c
in >> id;
bool found = false;
for (auto& m : mediaL
ist) {
if (m->getId() == id) {
cout << "请重新输入新信息:\n";
m->
input();
found = true;
break;
}
}
if (!found) cout << "该编号不存在！\n";
break;
}
case 5: {
if (mediaL
ist.empty()) {
cout << "物品库为空！\n";
break;
}
str
ing id;
cout << "请输入要删除的编号: ";
c
in >> id;
auto it = remove_if(mediaL
ist.beg
in(), mediaL
ist.end(),
[&](Media* m) { return m->getId() == id; });
if (it != mediaL
ist.end()) {
delete *it;
mediaL
ist.erase(it, mediaL
ist.end());
cout << "删除成功！\n";
} else {
cout << "该编号不存在！\n";
}
break;
}
case 6: {
int bookCount = 0, dvdCount = 0, pictureCount = 0;
for (auto m : mediaL
ist) {
if (dynamic_cast<Book*>(m)) bookCount++;
else if (dynamic_cast<DVD*>(m)) dvdCount++;
else if (dynamic_cast<Picture*>(m)) pictureCount++;
}
cout << "总物品数: " << mediaL
ist.size() << endl;
cout << "图书数量: " << bookCount << endl;
cout << "视频光盘数量: " << dvdCount << endl;
cout << "图画数量: " << pictureCount << endl;
break;
}
case 7: {
ofstream out("library.dat");
for (auto m : mediaL
ist) {
m->saveToFile(out);
}
out.close();
cout << "数据已保存到文件。\n";
break;
}
case 8: {
ifstream
in("library.dat");
if (!
in.
is_open()) {
cout << "无法打开文件。\n";
break;
}
mediaL
ist.clear();
while (
in.peek() != EOF) {
Media* m = Media::loadFromFile(
in);
if (m) mediaL
ist.push_back(m);
}
in.close();
cout << "数据已从文件加载。\n";
break;
}
case 9:
cout << "退出系统。\n";
break;
default:
cout << "无效选择，请重试。\n";
}
} while (choice != 9);
// 清理内存
for (auto m : mediaL
ist) delete m;
return 0;
}
```
---
##
本文介绍了一种在Swift语言中解决UITabBar点击事件的方法，通过在switch-case语句中为每个case添加花括号{}
扫一扫
1196
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
