[BREAKING] Simplify URL paths

content/notes/compiling.md

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+---
+title: Compiling [MAKE / GCC]
+description: 
+draft: false
+tags:
+  - c
+  - programming
+author: TrudeEH
+showToc: true
+---
+
+
+A compiler converts `C` code into machine code in 4 steps:
+1. **Preprocessing** (Convert all preprocessor instructions (`#…`) to C code.)
+2. **Compiling** (Convert `C` code to assembly.)
+3. **Assembling** (Compile the necessary libraries.)
+4. **Linking** (Merge the compiled code with the compiled libraries.)
+
+## Libraries
+
+Libraries are pre-written collections of code that can be reused in other programs. On *UNIX* systems, they are usually located in the `/lib/` and `/usr/include` directories.
+
+### Math.h
+
+For example, `math.h` is very useful to implement complex arithmetic operations.
+
+```C
+#include <math.h>
+double A = sqrt(9);
+double B = pow(2, 4);
+int C = round(3.14);
+int D = ceil(3.14);
+int E = floor(3.99);
+double F = fabs(-100);
+double G = log(3);
+double H = sin(45);
+double I = cos(45);
+double J = tan(45);
+```
+
+### Using Libraries
+
+To use a library, we first have to include it in the `C` code.
+
+```C
+#include <cs50.h> // cs50.h library will be included.
+```
+
+Then, the library must be linked at compile time (unless it is part of the C standard).
+
+```Shell
+gcc -o hello hello.c -lcs50
+./hello
+```
+
+## Optimization Flags
+
+- `-O2` Optimize for speed
+- `-O3` Optimize for speed aggressively
+- `-Os` Optimize for size
+- `-Og` Optimize for debugging
+- `-Oz` Optimize for size aggressively
+
+## Make
+
+`Make` Is a build automation tool that automates the process of compiling, linking and building executables.  
+An example `Makefile` could look like the following:
+
+```Makefile
+hello:
+	gcc -o hello hello.c -lcs50
+clean:
+	rm -f hello
+```
+
+```Shell
+make       # Compiles hello.c
+make clean # Removes the executable (hello) generated by the make command.
+```