Notes of my attempts to learn C++ more in depth.

For windows LLVM, MinGW64, ninja, cmake, visual studio, vscode etc. installed or extracted to folder. Also system environment variables path set to path of *.exe files. Not all examples require all tools.

Code structure is vscode Visual Studio clang format with attempt to follow google style guide best practice where possible. Alternate code formatting if used will be Chromium. Header guard follows google style guide <PROJECT>_<PATH>_<FILE>_H_ full path from project root.

For examples clang version is 15.0.2, gcc version is 12.2.0 is used and C++20 where possible (-std=c++20 in compiler).

Run these from command line. VSCode editor terminal is a good for editing and testing at the same time.

Basic compilation of cpp file with clang llvm in windows with CMakeLists.txt. Following command will generate ninja project in build folder with build.ninja in it. Here, C:\GitHub\CodeLab\learning_cpp\ex1 is the path to myapp.cpp file. If source path not specified then current path will be used for cpp.

cmake -DCMAKE_BUILD_TYPE:STRING=Debug "-DCMAKE_C_COMPILER:FILEPATH=C:\Program Files\LLVM\bin\clang.exe" "-DCMAKE_CXX_COMPILER:FILEPATH=C:\Program Files\LLVM\bin\clang++.exe" -SC:\GitHub\CodeLab\learning_cpp\ex1 -BC:\GitHub\CodeLab\learning_cpp\ex1\build -G Ninja

Finally using the following command will generate executable file. Since myapp was defined in CMakeLists.txt so it is used.

ninja myapp

In build folder myapp.exe will be generated. Now it can be run with following command.

./myapp.exe

For compilation with g++. Rest of the process to compile and run is same.

cmake -DCMAKE_BUILD_TYPE:STRING=Debug "-DCMAKE_C_COMPILER:FILEPATH=C:\mingw64\bin\gcc.exe" "-DCMAKE_CXX_COMPILER:FILEPATH=C:\mingw64\bin\g++.exe" -SC:\GitHub\CodeLab\learning_cpp\ex1 -BC:\GitHub\CodeLab\learning_cpp\ex1\build -G Ninja

Setting cl.exe path manually. Replace YOUR_VERSION with visual c++ compiler version.

cmake -DCMAKE_BUILD_TYPE:STRING=Debug "-DCMAKE_C_COMPILER:FILEPATH=C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/YOUR_VERSION/bin/Hostx64/x64/cl.exe" "-DCMAKE_CXX_COMPILER:FILEPATH=C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/YOUR_VERSION/bin/Hostx64/x64/cl.exe" -SC:\CodeLab\learning_cpp\ex1 -BC:\CodeLab\learning_cpp\ex1\build

Without setting manually.

cmake -DCMAKE_BUILD_TYPE:STRING=Debug -SC:\CodeLab\learning_cpp\ex1 -BC:\CodeLab\learning_cpp\ex1\build

The build folder will contain myapp.sln, myapp.vcxproj etc. myapp.sln can be opened in visual studio and compile from it. The following command will compile and generate executable from terminal.

cmake --build ./build

In build/Debug folder myapp.exe will be available.

./myapp.exe

Compiling c++ files with g++ compiler directly and generating executable.

g++ -O -c myapp.cpp -o myapp

Generate assembly files of various compiler optimization levels for comparison.

g++ -O3 -S -c myapp.cpp -o myapp_o3.s

g++ -O -S -c myapp.cpp -o myapp_o.s

Save intermediate files. It will save *.ii, *.o, *.s, *.exe files.

g++ -O3 --save-temps myapp.cpp -o myapp

Define compilation c++ version.

g++ -O2 -std=c++17 myapp.cpp -o myapp

Disassemble object code with objdump. First the object file needs to be generated if not available then disassemble.

g++ -O3 -c -std=c++17 myapp.cpp

objdump -d myapp.o

It comes with cuda toolkit and as of now should be able to compile C++17 code.

nvcc ex1/src/myapp.cpp -o myapp

./myapp

This project contains with multiple c++ source, header files in various directory. This project directory was structured somewhat following opencv source code. This example uses namespaces to prevent collision with other libraries, includes headers from include directory and manual code testing with assertion etc.

This will include header files from different directories like parent, sibling or others. All c++ files called needs to be passed for compilation. Here, src\basicmath\include is path to the header files used.

g++ -O3 -std=c++17 "-Isrc\basicmath\include" src\basicmath\tests\test_basicmath.cpp src\basicmath\src\adder.cpp -o myapp

Example of passing by reference and printing address. It includes multiple header and c++ files in different directories. Though one of the c++ files is not used for executable.

g++ -O3 -std=c++17 "-Isrc\basicmath\include" "-Isrc\basicmath\src" src\basicmath\tests\test_basicmath.cpp src\basicmath\src\adder.cpp src\basicmath\src\type_utils.cpp -o myapp

Functions defined in both array_utils.hpp, adder.hpp share same namespace bmath. Usage of fixed width integer types in loop and unsigned variable. Dynamic memory array allocation, release and equivalent vector insertion function.

g++ -O2 -std=c++17 "-Isrc\basicmath\include" src\basicmath\tests\test_array_declaration.cpp -o myapp src\basicmath\src\array_utils.cpp

Example of using CMakeLists.txt to generate multiple executable at once, memory leak, debugging function call stack.

Configure and generate project with given generator.

cmake -DCMAKE_BUILD_TYPE:STRING=Debug "-DCMAKE_C_COMPILER:FILEPATH=PATH_TO\clang.exe" "-DCMAKE_CXX_COMPILER:FILEPATH=PATH_TO\clang++.exe" -S./ex5 -B./ex5/build -G Ninja

Build all executable files in build folder.

cmake --build ./ex5/build/

Compile with clang++ with all diagnostics enabled. As seen by output warnings there was no warnings for memory leak.

clang++ -Weverything ex5/src/memory_leak.cpp -o out

Treat warnings like error. This will not generate executable until errors fixed.

clang++ -Werror -Weverything ex5/src/memory_leak.cpp -o out

Doing similar with g++ to see warnings and attempting to compile with -Werror flag. Again there was no warnings for memory leak.

g++ -Wall -Wextra ex5/src/memory_leak.cpp -o out

g++ -Wall -Wextra -Werror ex5/src/memory_leak.cpp -o out

Debugging from terminal with gdb. Resource for call stack and stack frame. Add -g flag for gdb debugging. Another faster option is to use vscode debug option.

g++ -std=c++17 -g -Wall -Wextra ex5/src/stack_frame_debug.cpp -o out

gdb out

Add break points.

break 43

break 34

break 25

break 18

break 10

Run program. If no breakpoints set it execute program and finish.

run

List 10 lines around the hit break point.

list

Print value of variable a.

print a

Watch for change in variable a.

watch a

Step in code and show code.

step

step

print a

list

Show all the program stack frames in call stack. It will show current function, line number and stack frames for the program in call stack.

backtrace

Select a frame and move up to outer frame by 1.

frame 2

up 1

Print verbose description of current frame.

info frame

Print local variables of selected frame.

info locals

Looking into local variable change. This will show the local value of a.

info locals

up

info locals

Quit gdb.

quit

Example of using address and undefined sanitizers for runtime memory and undefined error check. Also example of stack overflow, recursion to tail recursion conversion, execution timing with chrono, pass function reference to another function, pass function reference to another with std::function, doxygen format comments.

These codes nullptr_dereference.cpp, signed_int_overflow.cpp and uninitialized_variable_access.cpp compiles, runs and produces results. Yet running with sanitizer options produces runtime error on mistakes.

In stack_overflow.cpp example in debug or with address sanitizer stack overflow error is shown in run time. Code is same as below just name change.

clang++ -std=c++20 -g -O2 ex6/src/uninitialized_variable_access.cpp -o app.exe

./app.exe

clang++ -std=c++20 -g -O2 ex6/src/uninitialized_variable_access.cpp -o app.exe "-fsanitize=address,undefined" -fno-omit-frame-pointer

./app.exe

Conversion of recursive fibonacci to tail recursive, function timing, passing function with reference and std::function and doxygen comments.

There are also various fix options like --fix, that can apply fixes to code. In vscode settings searching clang tidy all checks can be enabled with chosen checks disabled. It shows more errors and warnings in UI and problems sections when enabled.

clang-tidy ex6/src/tail_recursion_debug.cpp --

clang-tidy "-checks=-,clang-analyzer-,-clang-analyzer-cplusplus*" ex6/src/tail_recursion_debug.cpp --