Compile-Time, Run-Time, and Execution Explained Simply

I learnt something today, i learnt some technical words like Run-time Error, Linting, compile-time. The truth is that i keep hearing and using this words without really knowing the meaning for real.

1. Run-time Error

• Definition: An error that occurs while the program is running, after it has successfully compiled.

• Example: Dividing by zero, accessing an array out of bounds, null pointer exceptions.

• Explanation: The code looks fine to the compiler, but something unexpected happens when the program executes.

• Example in Rust:

let x = 10;
let y = 0;
console.log(x / y); // Runtime error in some languages (Infinity in JS)
2. Linting

• Definition: Linting is the process of analyzing code without running it to find potential errors, style issues, or bad practices.

• Tools: ESLint (JS), Pylint (Python), RuboCop (Ruby).

• Example: Detecting unused variables, missing semicolons, or inconsistent indentation.

• Key point: Linting doesn’t execute the program, it just checks code quality and potential bugs.
  Example:

  fn main() {

  let text = "Hello, world!";
}

  Output:
  cargo clippy ─╯

  Checking rust_pract v0.1.0 (/Users/user/Downloads/workspace/AllAboutRust/rust_pract)

  warning: unused variable: `text`

  --> src/main.rs:3:9

  |

  3 | let text = "Hello, world!";

  | ^^^^ help: if this is intentional, prefix it with an underscore: `_text`

  |

  = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default

  warning: `rust_pract` (bin "rust_pract") generated 1 warning

  Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.14s

  we use cargo clippy for linting in rust.

---

3. Compile-time

• Definition: Errors or checks that happen when the code is being compiled (before running).

• Example: Syntax errors, type mismatches, undeclared variables.

• Explanation: The compiler prevents your program from running until these errors are fixed.

• Example in Rust:

let x: u32 = "Hello"; // Compile-time error: type mismatch
but wait what does it even mean for your code to be compiled?
Compiled means translating that high-level code (The code human can read and understand) into machine code (the binary’s, the computer language that is that 0’s and 1’s)

Thank you for your time:
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