In this challenge, your goal is to write a function that appends elements from one `std::vector<int>` to another, while guaranteeing **strong exception safety**. If an exception occurs during the append process—such as a memory allocation failure—the original destination vector should remain unchanged. This means you must ensure that either **all elements are successfully appended, or the vector is left exactly as it was before the operation began**.


#define CATCH_CONFIG_MAIN
#include <catch2/catch.hpp>


#include <vector>

void safe_vector_append(std::vector<int>& dest, const std::vector<int>& src);

TEST_CASE("Appends elements correctly when no exception occurs", "[safe_vector_append]") {
    std::vector<int> dest = {1, 2, 3};
    std::vector<int> src = {4, 5, 6};
    safe_vector_append(dest, src);
    REQUIRE(dest == std::vector<int>({1, 2, 3, 4, 5, 6}));
}

TEST_CASE("Appending empty src does not change dest", "[safe_vector_append]") {
    std::vector<int> dest = {10, 20};
    std::vector<int> src;
    safe_vector_append(dest, src);
    REQUIRE(dest == std::vector<int>({10, 20}));
}

TEST_CASE("Appending to empty dest copies src", "[safe_vector_append]") {
    std::vector<int> dest;
    std::vector<int> src = {7, 8, 9};
    safe_vector_append(dest, src);
    REQUIRE(dest == std::vector<int>({7, 8, 9}));
}

TEST_CASE("Multiple appends accumulate correctly", "[safe_vector_append]") {
    std::vector<int> dest = {1};
    std::vector<int> src1 = {2, 3};
    std::vector<int> src2 = {4};
    safe_vector_append(dest, src1);
    safe_vector_append(dest, src2);
    REQUIRE(dest == std::vector<int>({1, 2, 3, 4}));
}

test.cpp

A practical course on mastering exception handling in modern C++. Learn how to write robust code by detecting, throwing, and managing errors using exceptions. Each section introduces a new aspect of exception handling, followed by hands-on challenges inspired by real-world scenarios.

Understand the basics of exception handling in C++. Learn about try-catch blocks, throw statements, and the standard exception hierarchy.

Learn how to define and use your own exception classes for more descriptive error handling.

Discover how to write exception-safe code and manage resources properly using RAII.

Explore advanced techniques such as exception propagation, rethrowing, and exception specifications.

Challenge: Safe Vector Append

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