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Detailed Assembly Code Breakdown for C Program

This Markdown file provides an in-depth breakdown of three assembly functions extracted from an ELF file, representing a C program that takes user input, checks it against a computed value (derived from initial constants), and outputs a success or failure message. The messages are encoded using a ROT-3 cipher (subtract 3 from each character byte), and the shift function decodes and prints them. The analysis includes detailed line-by-line explanations, assembly code snippets, extrapolated C-like pseudocode, and logic flow represented in Mermaid diagrams.

Overview

• Program Logic: The main function prompts the user, reads an integer input, computes a target value (90 + 492 = 582, then 582 squared = 338724), and calls test with the input and target. The test function compares them and calls shift on the appropriate encoded string address. The shift function decodes the string in place by subtracting 3 from each byte and then prints it using `p

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Memory Analysis Tutorial Using x64dbg

This tutorial provides step-by-step instructions for analyzing a simple C program using x64dbg, focusing on memory allocation, initialization, and deallocation. The program dynamically allocates an array, initializes it with squared values, prints the fifth element, and frees the memory. We'll use x64dbg to set breakpoints, track heap allocations, observe array initialization, examine memory contents, and analyze the memory state after deallocation.

Prerequisites

• x64dbg: Download and install from https://x64dbg.com.
• C Compiler: Use a compiler like MinGW to compile the provided C program into a 64-bit executable.
• Program Code:

  #include <stdio.h>

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Debugging a Password Program with x64dbg

This guide outlines the steps to build and debug a simple C password-checking program using GCC in MSYS2 and x64dbg on Windows. The goal is to compile the program with specific flags, load it into x64dbg, set a breakpoint on strcmp, analyze function parameters, identify the correct password, and verify it. Mermaid diagrams are included to visualize the compilation and debugging processes.

Program Code

The C program (password.c) to debug is:

#include <stdio.h>
#include <string.h>

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Introduction to COBOL Programming with GnuCOBOL

Course Overview

This course provides a comprehensive introduction to COBOL programming using GnuCOBOL, an open-source COBOL compiler. Designed for beginners and intermediate programmers, the course covers fundamental programming concepts, data structures, practical applications, and advanced topics such as database integration. Each module builds on the previous one, ensuring a structured learning path that equips students with the skills to write robust COBOL programs for business applications.

Course Objectives

• Understand COBOL syntax and structure using GnuCOBOL.
• Master core programming concepts like variables, conditionals, and iteration.
• Implement data structures and basic algorithms in COBOL.

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Step-by-Step Execution of Iterative joinAll for [ ["x", "y"], ["z"] ]

This document walks through the execution of the non-recursive iterative joinAll function for the input [ ["x", "y"], ["z"] ], which generates all possible permutations of strings from the input lists, joined by underscores. The function produces ["x_z", "y_z"]. Each step of the iterative process is detailed below, with a Mermaid diagram visualizing the state of the algorithm, including the result and new_result lists. The diagrams are compatible with GitHub’s Mermaid renderer.

Iterative joinAll Implementation

The iterative solution builds combinations by maintaining a list of partial combinations (result) and updating it for each sublist.

def joinAll(lls):

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Walkthrough: Solving the joinAll Problem for Lists of Permutations

This walkthrough is designed to help you guide students through solving the joinAll problem, which involves generating all possible permutations of strings from a list of lists, joined by underscores. The goal is to provide a clear path to the solution while fostering understanding of key concepts like recursion, iteration, and Cartesian products. Below, we break down the problem, offer hints, suggest teaching strategies, provide a step-by-step solution approach, and include Mermaid diagrams to visualize the process, ensuring compatibility with GitHub's Mermaid renderer.

Problem Recap

The joinAll(lls) function takes a list of lists of strings and returns a list of all possible permutations, where each permutation is formed by selecting exactly one string from each sublist and joining them with underscores (_).

Example

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Problem Set: Lists of Permutations

Problem Description

You are tasked with writing a function joinAll(lls) which takes in a list of lists of strings and returns every permutation of elements from those lists, joined together with underscores (_).

Requirements:

1. The input is a list of lists of strings (e.g., [ ["a","b"], ["c"], ["d","e"] ]).
2. Each output string should be formed by picking exactly one element from each list in order, then joining them with underscores.

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🛡️ Network Security Learning Path (Zero → High-Paid Expert)

This roadmap combines structured curriculum (week-by-week) and milestone checkpoints so you can track progress whether you study part-time or full-time.

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📚 Phase 0: Foundations (6–9 months | ~500 hrs)

Goal: Build computer, networking, and programming basics.

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Building a Simple HTTP Server in Java: Problem Set

Introduction

This problem set guides you through building a basic HTTP server from scratch using Java's standard library, specifically the java.net.ServerSocket and java.net.Socket classes. The goal is to create a server that handles simple GET requests, parses incoming HTTP requests, and sends valid HTTP responses. We'll break it down into "tickets" – small, incremental tasks that build upon each other, simulating a real-world project workflow.

Prerequisites:

• Basic Java knowledge (sockets, I/O streams, file handling, string manipulation).
• No external libraries are allowed; use only Java's standard library (e.g., java.net, java.io, java.nio.file).
• Test your server using tools like curl (e.g., curl http://localhost:8080/) or a web browser.

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Building a Simple HTTP Server in JavaScript: Problem Set

Introduction

This problem set guides you through building a basic HTTP server from scratch using Node.js's http module. The goal is to create a server that handles simple GET requests, parses incoming HTTP requests, and sends valid HTTP responses. We'll break it down into "tickets" – small, incremental tasks that build upon each other, simulating a real-world project workflow.

Prerequisites:

• Basic JavaScript knowledge (Node.js, objects, file system operations).
• No external libraries are allowed; use Node.js's built-in modules (e.g., http, fs, url).
• Test your server using tools like curl (e.g., curl http://localhost:8080/) or a web browser.