• Type
• Layout
• Syntax
  • For loop vs while loop
• Execution flow
• See also

We use programming languages to talk to computers, but how does it work? Here we discuss a few concepts about programming languages including types, syntax, and execution flow.

Type

Static type means the type of every variable is known at compile-time, while dynamic type indicates that some variables have unknown type at compile-time, and are figured out later during run-time.

Layout

In a source code file, we can organize the code as the following for better readability.

1. Dependency imports
2. Global constants
3. Global variables
4. Type definition A which is based on type definition B
5. Type definition B
6. Function definition A which is based on function definition B
7. Function definition B

Syntax

For loop vs while loop

• Use the for loop when we know how many times we are looping.
• Use the while loop when we don't know beforehand how many times we will loop.

Execution flow

Human readable source code has to go through a sequence of operations to become electronic signals on a silicon chip.

• Source code to binary
  • Assembly
    • The assembler compiles the assembly code like ADD R0, R1 into the binary like 0001 0000 0001.
  • C
    • The GNU Compiler Collection (GCC) converts C code into the assembly specific to our CPU architecture like x86_64, amd64, or arm64.
    • The assembler compiles the assembly into a group of binaries, also called object files.
    • The linker combines the object files and libraries into the final binary.
  • English
    • The English compiler converts a set of English sentences into a binary.
• Binary to electrical signal
  • The CPU executes the binary by running electronic signals inside the logic gates.
    • Fetch
      • Fetch an instruction from memory.
    • Decode
      • Decode the instruction's operation and operands.
    • Execute
      • Execute the Arithmetic Logic Unit (ALU) operation or control flow adjustment.
    • Memory
      • Access memory to perform load (memory to register) or store (register to memory) operation.
    • Writeback
      • Save the result of the instruction execution to the register.

See also