Go Pointer Fundamentals: Manipulating Values Indirectly

This challenge will guide you through the fundamental concepts of pointers in Go. Understanding pointers is crucial for efficient memory management, working with complex data structures, and modifying values directly in memory. You will practice declaring, initializing, dereferencing, and passing pointers to functions.

Problem Description

Your task is to write a Go program that demonstrates the core functionalities of pointers. You will be working with a simple integer variable and exploring how pointers allow you to interact with its value indirectly.

Key Requirements:

1. Declare a pointer: Create a variable that holds the memory address of an integer.
2. Initialize a pointer: Assign the memory address of an existing integer variable to your pointer.
3. Dereference a pointer: Access and retrieve the value stored at the memory address pointed to by your pointer.
4. Modify value through pointer: Change the original integer's value by using its pointer.
5. Pass pointer to a function: Create a function that accepts an integer pointer and modifies the original integer's value within that function.

Expected Behavior:

Your program should clearly show each of these pointer operations and their effects on the original integer variable.

Edge Cases:

• What happens if you try to dereference a nil pointer? (For this challenge, we will not explicitly test this, but be aware of it).

Examples

Example 1: Basic Pointer Operations

Input: An integer variable `x` with the value 10.

Output:
Original value of x: 10
Address of x: [a memory address like 0x1040a124]
Value of pointer: [the same memory address as above]
Value at pointer: 10
Modified value of x: 25

Explanation:

1. An integer x is initialized to 10.
2. A pointer p is declared and initialized to hold the address of x.
3. The address of x and the value stored in p (which is the address of x) are printed.
4. The value stored at the memory address pointed to by p (i.e., the value of x) is printed.
5. The value of x is changed to 25 by dereferencing the pointer p and assigning a new value.
6. The modified value of x is printed.

Example 2: Modifying Value via Pointer within a Function

Input: An integer variable `num` with the value 5.

Output:
Initial value of num: 5
Value of num after function call: 15

Explanation:

1. An integer num is initialized to 5.
2. A function modifyValue is called, passing the address of num (a pointer).
3. Inside modifyValue, the pointer is dereferenced, and the value at that address is updated (e.g., multiplied by 3).
4. The original num variable's value is printed after the function call, demonstrating that it has been modified.

Constraints

• The challenge focuses on basic pointer manipulation and does not involve complex algorithms or large datasets.
• Input will be integers.
• No specific performance constraints are imposed, but the code should be clear and idiomatic Go.

Notes

• In Go, the & operator is used to get the memory address of a variable.
• The * operator is used to dereference a pointer (access the value it points to) or to declare a pointer type.
• When passing a pointer to a function, the function can directly modify the original variable.
• Consider how you will print the memory addresses themselves, as they are typically displayed in hexadecimal format.