C / C++

C vs C++

C and C++ are related but 2 different languages.

Style Guide

Google C++ Style Guide: https://google.github.io/styleguide/cppguide.html

Compilers and Build tools

Compilers: Clang (preferred) and GCC.
Build tools: no standard, CMake is probably the most popular; Gradle also supports C++; Google open sourced Bazel.

File Extensions

header files: .h, .hpp
source files: .c, .cpp, .cc

It does not matter which file extension to use.

Include

If a source file c.cc includes a header b.h, which includes a.h, c.cc can use all symbols declared in a.h.

Standard Template Library (STL) vs Standard Library

The original STL was developed separately, and was proposed to be included in C++ standard. Only part of it actually went into the standard, some parts were rejected while others were redesigned. That is why wikipedia says it "influenced many parts of the C++ Standard Library". You will not find the term "STL" in the standard, instead usually STL refers to container library, iterator library and algorithm

IDE

VS Code (free, code editor).
CLion (not free, full featured IDE).
Xcode (on macOS).

Where is C / C++ being used

OS: Linux is implemented in C (but NOT C++).
other languages: CPython is written in C; OpenJDK is using C++.
Web Browser: V8, the JS engine is in C++, used by node and Chrome.
graphics and games: Vulkan, which replaces OpenGL, is written in C; Unreal Engine is written in C++; Unity's runtime is in C++ (though programmers write C# on top of Unity).
servers: many companies, including Google and Facebook, use C++ extensively to build their servers.
databases: the most popular databases are often using C/C++: MySQL, Postgres, Redis, MongoDB.