我有一个小程序，它在同一个临界区运行 2 个线程并使用互斥锁。该程序运行良好。但我想画一个 UML，最好是活动或状态图，说明 2 个线程运行相同的临界区，而不是代码的不同部分。请帮我修改我的 UML。
下面是源代码：
#include <iostream>
#include <thread>
#include <mutex>
#include <stdio.h>
/* Global variables where both threads have access to*/
std::mutex myMutex;
int globalVariable = 1;
/* CRITICAL SECTION */
void hello()
{
myMutex.lock();
for (int counter =0 ; counter< 100; counter++){
//std::lock_guard<std::mutex> lock(myMutex);
printf("%d ",std::this_thread::get_id() ); //print the id of the thread that executes the for loop
globalVariable++;
}
printf("Thread with id = %d runs. Counter is %d \n", std::this_thread::get_id(), msg) ; //print the …我想找到一个所有成员数据都与某些值匹配的结构。
我做了一个小程序如下：
#include <iostream>
#include <vector>
using namespace std;
struct vlan {
int vlanId;
bool status;
};
vector<vlan> vlanTable;
int main(){
vlan tmp;
tmp.status = true;
tmp.vlanId = 1;
vector <vlan>::iterator flag = find(vlanTable.begin(), vlanTable.end(), tmp);
if ( flag != vlanTable.end()){
cout<<"found"<<endl;
}
else cout<<"not found"<<endl;
return 0;
}
它返回错误为：模板参数推导/替换在查找函数处失败。
有人可以帮助我吗？
C++ expressionThrow在https://en.cppreference.com/w/cpp/language/throw中定义为 a 。从语法上讲，它后面跟着一个异常类名。例如：
int a = 1, b = 0;
if (b==0){
string m ="Divided by zero";
throw MyException(m); //MyException is a class that inherit std::exception class
}
但是，我见过其他一些我不太理解的 throw 语法：
void MyFunction(int i) throw(); // how can we have an expression following a function definition?
或者在自定义异常类中，我们还有：
class MyException : public std::exception
{
public:
MyException( const std::string m)
: m_( m )
{}
virtual ~MyException() throw(){}; // what is throw() in this case?
const char* what() …