Namespaces
Variants

std:: jmp_buf

From cppreference.net
C++
Utilities library
Program support utilities
定义于头文件 <csetjmp>
typedef /* 未指定 */ jmp_buf ;

std::jmp_buf 类型是一种适用于存储调用环境恢复信息的数组类型。所存储的信息足以在程序的正确代码块处恢复执行并重新调用该代码块。浮点状态标志、打开的文件或任何其他数据的状态不会存储在 std::jmp_buf 类型的对象中。

示例

运行此代码 
#include <array>
#include <cmath>
#include <csetjmp>
#include <cstdlib>
#include <format>
#include <iostream>
std::jmp_buf solver_error_handler;
std::array<double, 2> solve_quadratic_equation(double a, double b, double c)
{
    const double discriminant = b * b - 4.0 * a * c;
    if (discriminant < 0)
        std::longjmp(solver_error_handler, true); // 跳转至错误处理程序
    const double delta = std::sqrt(discriminant) / (2.0 * a);
    const double argmin = -b / (2.0 * a);
    return {argmin - delta, argmin + delta};
}
void show_quadratic_equation_solution(double a, double b, double c)
{
    std::cout << std::format("求解 {}x² + {}x + {} = 0...\n", a, b, c);
    auto [x_0, x_1] = solve_quadratic_equation(a, b, c);
    std::cout << std::format("x₁ = {}, x₂ = {}\n\n", x_0, x_1);
}
int main()
{
    if (setjmp(solver_error_handler))
    {
        // 求解器的错误处理程序
        std::cout << "无实数解\n";
        return EXIT_FAILURE;
    }
    for (auto [a, b, c] : {std::array{1, -3, 2}, {2, -3, -2}, {1, 2, 3}})
        show_quadratic_equation_solution(a, b, c);
    return EXIT_SUCCESS;
}

输出： 

求解 1x² + -3x + 2 = 0...
x₁ = 1, x₂ = 2
求解 2x² + -3x + -2 = 0...
x₁ = -0.5, x₂ = 2
求解 1x² + 2x + 3 = 0...
无实数解

参见

保存执行上下文
(函数宏)
跳转到指定位置
(函数)
C 文档 关于 jmp_buf