std::jmp_buf
From cppreference.com
| Defined in header <csetjmp>
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typedef /* unspecified */ jmp_buf;
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The std::jmp_buf type is an array type suitable for storing information to restore a calling environment. The stored information is sufficient to restore execution at the correct block of the program and invocation of that block. The state of floating-point status flags, or open files, or any other data is not stored in an object of type std::jmp_buf.
Example
Run this code
#include <array>
#include <cmath>
#include <csetjmp>
#include <cstdlib>
#include <print>
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); // jumps to error handler
const double Δ = std::sqrt(discriminant) / (2.0 * a);
const double β = -b / (2.0 * a);
return {β - Δ, β + Δ};
}
void show_quadratic_equation_solution(double a, double b, double c)
{
std::print("Solving {}⋅x² + {}⋅x + {} = 0...\n", a, b, c);
auto [x₁, x₂] = solve_quadratic_equation(a, b, c);
std::print("x₁ = {}, x₂ = {}\n\n", x₁, x₂);
}
int main()
{
if (setjmp(solver_error_handler))
{
// Error handler for solver
std::print("No real solutions\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;
}
Output:
Solving 1⋅x² + -3⋅x + 2 = 0...
x₁ = 1, x₂ = 2
Solving 2⋅x² + -3⋅x + -2 = 0...
x₁ = -0.5, x₂ = 2
Solving 1⋅x² + 2⋅x + 3 = 0...
No real solutions