C ++ Try Catch Block没有捕获异常

Question

我是C ++的初学者，并试图创建一个简单的控制台程序来计算线性方程的'm'和'b'...来解析用户提供的输入双，我使用的是字符串流并尝试使用-catch块检查错误输入。 即使catch块具有全局异常，持久性错误也会继续跟踪[方程Solver.exe中的0x74c8b9bc处的未处理异常：Microsoft C ++异常：[rethrow]在内存位置0x00000000 ..]

double XOne;`enter code here`
double YOne;
double XTwo;
double YTwo;
bool inputCheck = false;
while (inputCheck == false)
{
    Clear();
    WriteLine("**Linear Equation**");
    Write("X1: ");
    string xone = ReadLine();
    Write("Y1: ");
    string yone = ReadLine();
    Write("X2: ");
    string xtwo = ReadLine();
    Write("Y2: ");
    string ytwo = ReadLine();
    try
    {
        stringstream s1(xone);
        if (s1 >> XOne) { s1 >> XOne; } else { throw; }
        stringstream s2(yone); // consider I give an invalid input for this variable
        if (s2 >> YOne) { s2 >> YOne; } else { throw; } // this doesn't solve the problem
        stringstream s3(xtwo);
        if (s3 >> XTwo) { s3 >> XTwo; } else { throw; }
        stringstream s4(ytwo);
        if (s4 >> YTwo) { s4 >> YTwo; } else { throw; }
    }
    catch (...) { WriteLine("Invalid Input"); ReadLine(); }
}

LinearEquation equation;
equation.Initialize(XOne, YOne, XTwo, YTwo);
stringstream s5;
s5 << equation.m;
string m = s5.str();
stringstream s6;
s6 << equation.b;
string b = s6.str();
Write("Y = ");
Write(m);
Write("X + ");
WriteLine(b);
ReadLine();

编辑第一个建议就像一个魅力......谢谢！ 这是我根据评论者修改后的代码。

double XOne;
double YOne;
double XTwo;
double YTwo;
bool inputCheck = false;
while (inputCheck == false)
{
    Clear();
    WriteLine("**Linear Equation**");
    Write("X1: ");
    string xone = ReadLine();
    Write("Y1: ");
    string yone = ReadLine();
    Write("X2: ");
    string xtwo = ReadLine();
    Write("Y2: ");
    string ytwo = ReadLine();
    try
    {
        stringstream s1(xone);
        if (s1 >> XOne) { s1 >> XOne; } else { throw runtime_error("Invalid Input"); }
        stringstream s2(yone);
        if (s2 >> YOne) { s2 >> YOne; } else { throw runtime_error("Invalid Input"); }
        stringstream s3(xtwo);
        if (s3 >> XTwo) { s3 >> XTwo; } else { throw runtime_error("Invalid Input"); }
        stringstream s4(ytwo);
        if (s4 >> YTwo) { s4 >> YTwo; } else { throw runtime_error("Invalid Input"); }
    }
    catch (runtime_error e) { WriteLine(e.what()); ReadLine(); }
}

LinearEquation equation;
equation.Initialize(XOne, YOne, XTwo, YTwo);
stringstream s5;
s5 << equation.m;
string m = s5.str();
stringstream s6;
s6 << equation.b;
string b = s6.str();
Write("Y = ");
Write(m);
Write("X + ");
WriteLine(b);
ReadLine();

Answer 1

没有参数的throw只能在处理异常时使用（即在catch块或直接或间接从catch块调用的函数中），否则你必须使用带有参数的throw，这通常是一个异常对象某种。

如果在未处理异常时执行throw将调用std::terminate来结束程序。

例如（在#include <stdexcept> ）

throw std::runtime_error("Bad input");