Commit 80c3b9bd authored by Alexander Hirsch's avatar Alexander Hirsch

Add ex04

parent c532ffc1
# Exercise Sheet 4
*due on 26 November 2019*
## Task 1 (4 Points)
You are given the following definition of a person:
struct Person {
std::string first_name;
std::string last_name;
int age;
- Implement comparison operators: `==` and `!=`
- Implement relational operators: `<`, `<=`, `>`, and `>=`
- Implement the operator `<<` for `std::ostream`, so we can write:
std::cout << Person{"John", "Doe", 42} << std::endl;
- For primitive types a function `std::to_string` is provided in the standard library.
Implement a similar function `to_string` for `Person`.
Justify whether your function / operator is a regular function, regular member function, static member function, friend function.
- Put your whole implementation (including `to_string`) in a namespace (eg `foo`).
Explain why this is possible without `using namespace foo`:
foo::Person p1{"John", "Smith", 42};
std::cout << to_string(p1) << std::endl;
## Task 2 (3 Points)
The folder `task2` contains code and build instructions for a shared library and an executable which uses the shared library.
The shared library features two functions `random_number` and `just_a_print` inside the `foo` namespace.
Your task is to create an *interceptor* library:
- `random_number` should be replaced with a function that always returns `4` for improved determinism
- `just_a_print` should be wrapped so that some text is printed before and after the original function is executed
Running the executable with and without the interceptor library could look like this:
$ ./executable
Random Number: 880806932
Just a print to stdout, nothing else
$ LD_PRELOAD=$PWD/ ./executable
Random Number: 4
some text before
Just a print to stdout, nothing else
some text after
*Hint:* For Linux, have a look at the related man-pages like *ld-linux(8)*.
## Inday Students
This year's Inday Students event is scheduled for 26 November.
Let me know if you cannot attend the PS because of this.
cmake_minimum_required(VERSION 3.8)
project(example LANGUAGES CXX)
add_library(foo SHARED libFoo/foo.cpp)
target_include_directories(foo PUBLIC libFoo)
add_executable(executable executable.cpp)
target_link_libraries(executable foo)
#include <iostream>
#include "foo.hpp"
int main()
std::cout << "Random Number: " << foo::random_number() << "\n\n";
#include "foo.hpp"
#include <iostream>
#include <limits>
#include <random>
namespace foo {
int random_number()
static std::random_device device;
static std::mt19937 rng(device());
static std::uniform_int_distribution<int> dist(0, std::numeric_limits<int>::max());
return dist(rng);
void just_a_print()
std::cout << "Just a print to stdout, nothing else\n";
} // end namespace foo
#ifndef FOO_HPP
#define FOO_HPP
namespace foo {
int random_number();
void just_a_print();
} // end namespace foo
#endif // FOO_HPP
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