How C Runs: Reading Path Through Assembly, Memory, and the CPU

About This Route

Central question: How does a C program become running behavior on a machine?

This route maps familiar C constructs to lower-level execution counterparts. It connects expressions, variables, functions, pointers, and arrays to CPU instructions, registers, stack frames, memory addresses, executable files, and process execution.

Assembly is used as a bridge, not as the final learning goal. The purpose is to build a programmer-facing mental model of C program execution.

Contents

1. What Does It Mean for a C Program to Run?
2. Why Assembly Is the Bridge Between C and the Machine
3. How Simple C Expressions Become CPU Operations
4. Registers as the CPU’s Working Space
5. Local Variables and the Stack
6. Function Calls and Stack Frames
7. Pointers as Address Values
8. Arrays and Structs as Address Calculations
9. From Source Code to Executable File
10. From Executable File to Running Process
11. Final Mental Model: C Concepts and Their Lower-Level Counterparts

Reading Path

Read the notes in order. The path starts with the meaning of program execution, then uses assembly to expose how C maps onto machine behavior before moving through registers, stack frames, pointers, arrays, executable files, and processes.

What You Will Understand

• A C program does not run as C source code directly.
• C expressions and variables eventually correspond to instructions, registers, memory locations, and address calculations.
• Function calls, local variables, pointers, arrays, and structs have lower-level execution counterparts.
• Executable files and running processes are related but distinct stages in the path from source code to behavior.