pointers

src/Learning-C/Pointers/introduction.md

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+# Pointers
+
+pointers are variables that store memory addresses. They allow direct manipulation of memory, which is a powerful feature but also requires careful handling to avoid errors.
+
+#### Basic Pointer Syntax
+
+- Declaring a pointer: `int *ptr;` declares a pointer named `ptr` that can point to an integer value.
+- Dereferencing a pointer: `*ptr` refers to the value stored at the memory address pointed to by `ptr`.
+
+#### Understanding declarations
+
+`int n;` to get an int just use n
+
+`int n[3]` to get an int just use n[i]
+
+`int foo(int n, float n1);` to get an int just call foo with related inputs.
+
+`int *n;` to get an int just dereference n
+
+
+### Pass by Value and Pass by Reference
+
+#### Pass by value
+
+##### Advantages
+
+1. Easy to understand
+   1. you just pass copies, nothing fancy to deference
+2. Safe
+   1. Original data won't be modified by the called function
+
+##### Disadvantages
+
+3. Performance overhead
+   1. A big object like a struct to be copied it's really bad performance wise. Time consuming and memory intensive.
+4. Short reach(Lack of direct acess)
+   1. Called functions can only modify local copies. (This can be a good thing too) k
+Declarations tell us 'How to use'
+
+#### Pass by reference
+
+##### Advantages
+
+1. Efficiency
+   1. You just pass an address, it can point to a gigantic structure, not a problem.
+2. Direct access
+   1. can modify data outside the called function. This trick allows us to return multiple values from a function.
+
+##### Disadvantages
+
+1. Can be complex to understand
+    1. You have to dereference the pointer to get the value.
+
+
+Type casting to VOID* is a way to pass any type of data to a function. aka generic. It's a way to pass data without knowing the type of data. "we'll let you know bro".
+
+malloc is a function that allocates some memory in the heap. It returns a void pointer doesn't care if you give the pointer a type. It's a way to allocate memory dynamically.
+
+we can do `void * `arithmetic with a GNU extention. 
+
+> GNU Extention refers to additional language features or behaviour provided by GCC that go beyond the standard C language.
+
+GNU C provided an extention called Pointer Arithmetic on `void *` that allows performing arithmetic operations on `void *` pointers by treating them as byte pointers. This extention is by default enabled in GCC.
+
+The pointer arithmetic is done is done in terms of the size of char(1 byte) rather than the size of the pointer type. 
+
+