cpp_getting_started.md

C++ Getting Started

Installing a C++ compiler

Make sure you have a C++ compiler like g++ or clang++. On Debian based distros (Ubuntu, Pop!_OS etc) you can get all necessary build tools using

# apt update
# apt install build-essential

If you're using some other linux distro you definitely know how to do that ¬‿¬

On Windows the standard way is to install Microsoft Visual C++ in Visual Studio Installer but it's too big. Better use WSL or MinGW

An example C++ workflow

Workflow

clone the repo

$ git clone https://github.com/YOUR_USERNAME/cses-repository
$ cd cses-repository

code the solution

$ vim missing_number.cpp

compile and run

$ g++ missing_number.cpp -o missing_number
$ ./missing_number

commit and push on successfull completion

$ git add missing_number.cpp
$ git commit -m "solve missing_number.cpp"
$ git push

You can redirect the input stream to read from a file instead of typing it again and again during each run with

$ ./missing_number < input.txt

Similarly you could redirect the output to a file and diff it with a file containing actual_output to check the correctness

$ ./missing_number < input.txt > output.txt
$ diff actual_output.txt output.txt
# or in a single command without a temporary file
$ ./missing_number < input.txt | diff - actual_output.txt

Do .gitignore your temporary input and output files

An xmake based C++ workflow

manually passing compiler options to g++ or clang++ like below is too lengthy and messy

$ g++ -std=c++20 -Wall -Wextra -Wpedantic -Wshadow -g -fsanitize=address,undefined missing_number.cpp -o missing_number

checkout Diagnostic section of hackingcpp Beginner's Guide for more info on the above flags

Also you'll have to manually install and link other libraries you may use. If you want your code editor's LSP (Language Server Protocol) to pick up these extra compiler flags you'll have to create a compile_commands.json file (You can generate one with Bear). You could use a good old Makefile to wrap over all these build details but I personally find using a simple build tool like xmake much easier.

You can find the installation instructions for xmake here

To initialize a xmake project in the repo run

$ xmake create -l c++ -P .

Here's my xmake config file with flags and tools I commonly use,

xmake.lua

add_rules("mode.debug", "mode.release")

set_languages("c++20") -- sets the compiler to use c++ 20
set_policy("build.sanitizer.address", true) -- links address sanitizer that helps you catch invalid memory usage, leaks etc early
set_policy("build.sanitizer.undefined", true) -- links undefined behavior sanitizer that helps you catch UBs like integer overflows, dereferencing null pointers etc
add_rules("plugin.compile_commands.autoupdate") -- automatically generates a `compile_command.json` for you
add_cxxflags("-Wall -Wextra -Wpedantic -Wshadow -g") -- enables stricter warnings. As a bonus due to generated `compile_command.json`, you're LSP will also report these warnings

-- add_requires("dbg-macro")
-- add_packages("dbg-macro")

for _, file in ipairs(os.files("src/*.cpp")) do
  local name = path.basename(file)

  target(name)
    set_kind("binary")
    add_files(file)
end

Workflow

code the solution

$ vim src/missing_number.cpp

build and run

$ xmake && xmake run missing_number

A better way to print STL classes like std::vector for debugging

You'll find yourself writing code to print vectors, deques etc for debugging. To save you time you could use this library dbg-macro

install dbg-macro with xmake

$ xmake install dbg-macro

uncomment these lines in xmake.lua

add_requires("dbg-macro")
add_packages("dbg-macro")

you get the dbg(...) macro by #include "dbg.h". Make sure to remove/comment these before you submit as it's for local debugging.

Some resources on C++

• hackingcpp Beginner's Guide
• cppreference