1 HelloWorld | KaiGuoV5

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1.1 Compile

1.1.1 Preprocess

✅

Details:

Remove Comments: Delete the comments in the source code.

Process macro definitions: Expand macro definitions.

Process conditional compilation: Selectively include or exclude code based on conditional compilation directives such as #ifdef, #ifndef, #if.

Process inclusion of files: Insert the contents of header files into the source file, forming a single file.

Process other preprocessing directives.

1.1.2 Compile

✅

Details:

Translate the preprocessed source code into assembly language code.

1.1.3 Assemble

✅

Details:

Translation of assembly code into machine code (object files)

1.1.4 Link

✅

Details:

Link all object files and possible library files together, resolve symbol references, and generate the final executable file.

If shared libraries (dynamic link libraries) are used, the linker may generate dynamic link library files (.so or .dll).

1.2 Terminology

🔴

Compiler Error: program not compilable, compiler will stop

⚠️

Compiler Warning: program compilable, compiler will continue, but there is a problematic piece of code that might lead to runtime bugs

1.3 Compiler Flags

⚠️

Recommended compiler flags for your first programs

g++ -std=c++20 -Wall -Wextra -Wpedantic -Wshadow input.cpp -o output

Flags	Function
-std=c++20	Sets compiler to the C++20 standard. Highly Recommended.
`-Wall` `-Wpedantic` `-Wextra` `-Wshadow`	Enable compiler warnings. Highly recommended. These don't really activate all warnings, but rather the most important ones that don't produce too much (false positive) noise.

It's 2023 – set your compiler to C++20 (or at least to C++17 if you have to use an older compiler).

🚫

Don't Use using namespace std;!

Many code examples / tutorials show something like this:

… to avoid qualifying cout with std::.

But:

using a namespace drags all symbols from that namespace into the global namespace. This can lead to name conflicts and ambiguities and in some cases even bugs that will only manifest at runtime and are very hard to detect.

Polluting the global namespace with all symbols from other namespaces is a serious liability in any production code base and you should avoid this anti-pattern from the very start.

1.4 Library

Write later

1.4.1 Static Library

fixed at compile time (baked into the executable file, not changeable at runtime)

1.4.2 Shared Library

changeable at runtime (possibly by user input)