NAME¶

std::jmp_buf - std::jmp_buf

Synopsis¶

Defined in header <csetjmp>
typedef /* unspecified */ jmp_buf;

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 <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); // Go to error handler

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("Solving {}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))
{
// Error handler for solver
std::cout << "No real solution\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 1x² + -3x + 2 = 0...
x₁ = 1, x₂ = 2

Solving 2x² + -3x + -2 = 0...
x₁ = -0.5, x₂ = 2

Solving 1x² + 2x + 3 = 0...
No real solution

See also¶

setjmp saves the context
(function macro)
longjmp jumps to specified location
(function)
C documentation for
jmp_buf