vs2022#include <string> // #ifndef EXAMPLE_H // #define EXAMPLE_H extern "C" { bool my_cpp_read(const char * FullName); // 读文件 bool my_cpp_write(const char* FullName);// 写文件 void hello_world() { std::cout << "Hello, World!" << std::endl; } int plusfun(int a, int b,int c) { return 123456; } int add_numbers(int a, int b) { return a + b; } }

这段代码看起来是一个 C++ 的头文件，其中定义了一些函数和变量，并且使用了 C 语言的 extern "C" 语法来确保这些函数能够被 C 代码调用。其中包括了读写文件的函数和一些简单的数学运算函数，还有一个打印 "Hello, World!" 的函数。此外，这段代码使用了 C++ 标准库中的 string 类型，需要包含 <string> 头文件。头文件中还包含了经典的预编译指令，用于防止头文件被重复包含。

相关问题

已知main.cpp: #include "mywidget.h" #include <QApplication> volatile bool start=1; int main(int argc, char *argv[]) { QApplication a(argc, argv); MyWidget w; w.show(); return a.exec(); } 已知mywidget.h: #ifndef MYWIDGET_H #define MYWIDGET_H #include <QWidget> #include <QDebug> extern volatile bool start; QT_BEGIN_NAMESPACE namespace Ui { class MyWidget; } QT_END_NAMESPACE class MyWidget : public QWidget { Q_OBJECT public: MyWidget(QWidget *parent = nullptr); ~MyWidget(); private: Ui::MyWidget *ui; private slots: void closeEvent(QCloseEvent *event); }; #endif // MYWIDGET_H 已知mywidget.cpp: #include "mywidget.h" #include "ui_mywidget.h" void conf(void) { for(;;) { if(start == 1) { qDebug()<<"Windows Open 1"; } else { qDebug()<<"Windows Close -999"; break; } } } MyWidget::MyWidget(QWidget *parent) : QWidget(parent) , ui(new Ui::MyWidget) { ui->setupUi(this); conf(); } void MyWidget::closeEvent(QCloseEvent *event) { start = 0; } MyWidget::~MyWidget() { delete ui; } 现在这个陷入了死循环，请帮我优化一下

您可以在 `conf` 函数中添加一个延时，以避免陷入死循环。您可以使用 `QThread::msleep` 函数来实现延时。

以下是修改后的代码：

#include "mywidget.h"
#include "ui_mywidget.h"
#include <QThread>

void conf(void)
{
    for(;;)
    {
        if(start == 1)
        {
            qDebug() << "Windows Open 1";
            // 延时一段时间，例如100毫秒
            QThread::msleep(100);
        }
        else
        {
            qDebug() << "Windows Close -999";
            break;
        }
    }
}

MyWidget::MyWidget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::MyWidget)
{
    ui->setupUi(this);
    // 在构造函数中调用 conf 函数，启动循环
    QMetaObject::invokeMethod(this, "conf", Qt::QueuedConnection);
}

void MyWidget::closeEvent(QCloseEvent *event)
{
    start = 0;
}

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

通过在循环中添加延时，程序将暂停一段时间再进行下一次循环迭代，避免了陷入无限循环的情况。

希望这个优化对您有帮助。如果您还有其他问题，请随时提问。

<iostream>头文件源码

下面是iostream头文件的源码：

#ifndef _IOSTREAM_H
#define _IOSTREAM_H

#include <ios>      // basic_ios, streampos, streamoff, etc.
#include <streambuf>    // basic_streambuf
#include <istream>  // basic_istream
#include <ostream>  // basic_ostream
#include <cstdio>   // EOF, FILE
#include <wchar.h>  // wchar_t

namespace std {
    extern istream cin;    // standard input stream
    extern ostream cout;   // standard output stream
    extern ostream cerr;   // standard error (output) stream
    extern ostream clog;   // standard logging (output) stream

    template <class charT, class traits = char_traits<charT>>
    class basic_iostream : public basic_ios<charT, traits> {
    public:
        using char_type = charT;
        using int_type = typename traits::int_type;
        using pos_type = typename traits::pos_type;
        using off_type = typename traits::off_type;
        using traits_type = traits;

        // constructors
        explicit basic_iostream(basic_streambuf<charT, traits>* sb);
        virtual ~basic_iostream();

        // delete copy and move constructors and assignments
        basic_iostream(const basic_iostream&) = delete;
        basic_iostream& operator=(const basic_iostream&) = delete;
        basic_iostream(basic_iostream&&) = delete;
        basic_iostream& operator=(basic_iostream&&) = delete;

        // basic_iostream operations
        basic_ios<charT, traits>* tie() const;
        basic_ios<charT, traits>* tie(basic_ios<charT, traits>* tiestr);
        basic_streambuf<charT, traits>* rdbuf() const;
        void rdbuf(basic_streambuf<charT, traits>* sb);

        // conversions
        operator void*() const;
        bool operator!() const;

        // unformatted input
        int_type get();
        basic_iostream<charT, traits>& get(char_type& c);
        basic_iostream<charT, traits>& get(char_type* s, streamsize n);
        basic_iostream<charT, traits>& get(char_type* s, streamsize n, char_type delim);
        basic_iostream<charT, traits>& getline(char_type* s, streamsize n);
        basic_iostream<charT, traits>& getline(char_type* s, streamsize n, char_type delim);
        basic_iostream<charT, traits>& ignore(streamsize n = 1, int_type delim = traits::eof());
        basic_iostream<charT, traits>& read(char_type* s, streamsize n);
        streamsize readsome(char_type* s, streamsize n);

        // unformatted output
        basic_iostream<charT, traits>& put(char_type c);
        basic_iostream<charT, traits>& write(const char_type* s, streamsize n);

        // formatted input
        basic_iostream<charT, traits>& operator>>(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
        basic_iostream<charT, traits>& operator>>(basic_istream<charT, traits>& (*pf)(basic_istream<charT, traits>&));
        basic_iostream<charT, traits>& operator>>(basic_streambuf<charT, traits>* sb);

        basic_iostream<charT, traits>& operator>>(bool& n);
        basic_iostream<charT, traits>& operator>>(short& n);
        basic_iostream<charT, traits>& operator>>(unsigned short& n);
        basic_iostream<charT, traits>& operator>>(int& n);
        basic_iostream<charT, traits>& operator>>(unsigned int& n);
        basic_iostream<charT, traits>& operator>>(long& n);
        basic_iostream<charT, traits>& operator>>(unsigned long& n);
        basic_iostream<charT, traits>& operator>>(long long& n);
        basic_iostream<charT, traits>& operator>>(unsigned long long& n);
        basic_iostream<charT, traits>& operator>>(float& f);
        basic_iostream<charT, traits>& operator>>(double& f);
        basic_iostream<charT, traits>& operator>>(long double& f);
        basic_iostream<charT, traits>& operator>>(void*& p);

        basic_iostream<charT, traits>& operator>>(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
        basic_iostream<charT, traits>& operator>>(basic_istream<charT, traits>& (*pf)(basic_istream<charT, traits>&));
        basic_iostream<charT, traits>& operator>>(basic_streambuf<charT, traits>* sb);

        // formatted output
        basic_iostream<charT, traits>& operator<<(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
        basic_iostream<charT, traits>& operator<<(basic_ostream<charT, traits>& (*pf)(basic_ostream<charT, traits>&));
        basic_iostream<charT, traits>& operator<<(basic_streambuf<charT, traits>* sb);

        basic_iostream<charT, traits>& operator<<(bool n);
        basic_iostream<charT, traits>& operator<<(short n);
        basic_iostream<charT, traits>& operator<<(unsigned short n);
        basic_iostream<charT, traits>& operator<<(int n);
        basic_iostream<charT, traits>& operator<<(unsigned int n);
        basic_iostream<charT, traits>& operator<<(long n);
        basic_iostream<charT, traits>& operator<<(unsigned long n);
        basic_iostream<charT, traits>& operator<<(long long n);
        basic_iostream<charT, traits>& operator<<(unsigned long long n);
        basic_iostream<charT, traits>& operator<<(float f);
        basic_iostream<charT, traits>& operator<<(double f);
        basic_iostream<charT, traits>& operator<<(long double f);
        basic_iostream<charT, traits>& operator<<(const void* p);
        basic_iostream<charT, traits>& operator<<(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
        basic_iostream<charT, traits>& operator<<(basic_ostream<charT, traits>& (*pf)(basic_ostream<charT, traits>&));
        basic_iostream<charT, traits>& operator<<(basic_streambuf<charT, traits>* sb);
    };

    // typedefs
    using iostream = basic_iostream<char>;
    using wiostream = basic_iostream<wchar_t>;

    // manipulators
    extern basic_istream<char>& ws(basic_istream<char>& is);
    extern basic_istream<wchar_t>& ws(basic_istream<wchar_t>& is);

    // object instances
    extern istream cin;
    extern ostream cout;
    extern ostream cerr;
    extern ostream clog;

    // non-member functions
    template <class charT, class traits>
    basic_istream<charT, traits>& flush(basic_istream<charT, traits>& is);
    template <class charT, class traits>
    basic_ostream<charT, traits>& flush(basic_ostream<charT, traits>& os);

    template <class charT, class traits>
    basic_istream<charT, traits>& ws(basic_istream<charT, traits>& is);

    template <class charT, class traits>
    void swap(basic_ios<charT, traits>& a, basic_ios<charT, traits>& b) noexcept;
}

#endif /* _IOSTREAM_H */

该头文件定义了C++标准输入输出流（cin、cout、cerr、clog）以及基本的输入输出流对象。同时还定义了一系列输入输出的操作符和控制符。