leejunkim

Programming languages

3 min read

  • https://www.learncpp.com/cpp-tutorial/introduction-to-programming-languages/

  • Source code ---(compiler)-⇒ assembly code ---(assembler)-⇒ object files (machine code + metadata + etc) ---(linker)⇒ executable

  • machine code

    • set of 0 and 1s (binary)
    • consists of instructions that tell the CPU what operations to perform
    • the low-level binary code that the CPU can directly execute (not an executable)

  • object files

    • .obj or .o files
    • contain machine code along with metadata and information about symbols
    • typically not directly executable

  • linker

    • takes one or more object files and combines into an executable
    • resolves references between object files, includes necessary libraries, and sets up the executable’s entry point

  • Compilers

    • Compiles source code written in high-level language into assembly
    • modern c++ compilers often includes the assembler so it just compiles directly into machine code
    • some modern compilers
      • clang
      • gcc

  • Interpreters

    • interpreter is a program that directly executes the instructions in the source code without requiring them to be compiled into an executable first

  • CPUs are only capable of understanding machine language

    • Each CPU family has different syntax for assembly/machine code depending on the CPU family
    • Each CPU family has its own architecture and instruction set architecture (ISA) that defines assembly/machine code
    • ex. x86 uses commands like mov

Options in IDE

  • Build compiles all modified code files in the project or workspace/solution, and then links the object files into an executable. If no code files have been modified since the last build, this option does nothing.
  • Clean removes all cached objects and executables so the next time the project is built, all files will be recompiled and a new executable produced.
  • Rebuild does a “clean”, followed by a “build”.
  • Compile recompiles a single code file (regardless of whether it has been cached previously). This option does not invoke the linker or produce an executable.
  • Run/start executes the executable from a prior build. Some IDEs (e.g. Visual Studio) will invoke a “build” before doing a “run” to ensure you are running the latest version of your code. Otherwise (e.g. Code::Blocks) will just execute the prior executable.

Configuring your compiler: Build configurations

Use the debug build configuration when developing your programs. When you’re ready to release your executable to others, or want to test performance, use the release build configuration.

  • Build configuration (build target)
    • A collection of project settings that determines how your IDE will build your project
    • What the executable will be named, that directories the IDE will look for in other code and library files, how much to have the compiler optimize, etc
  • debug configuration
    • designed to help you debug your program, and is generally the one you will use when writing your programs
    • turns of all optimizations and includes debugging info
    • programs much slower but much easier to debug
  • release configuration
    • used when releasing your program to the public
  • FOr VSCode
    • Above the “${file}” line, add a new line containing the following command (one per line) when debugging: “-ggdb”
    • Above the “${file}” line, add new lines containing the following commands (one per line) for release builds: “-O2”, “-DNDEBUG”,

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