Logic Visualizer | C/C++

Visual Logic Representation of Directional Movement Code

This document visualizes the logic of a C program that updates coordinates based on user input commands for direction (N, S, E, W) and provides detailed explanations of the code's flow and structure.

Prompt

#include 

int main() {
  int x = 0, y = 0, c;
    char s[9];
    scanf("%d", &c);
    for (int i = 0; i != c; i++) {
        fgets(s, 9, stdin);
        switch (s[0]) {
            case 'N': {
                y = y + (int)s[7]; 
                break;
            }
            case 'S': {
                y = y - (int)s[7]; 
                break;
            }
            case 'E': {
                x = x + (int)s[6]; 
                break;
            }
            case 'W': {
                x = x + (int)s[6]; 
                break;
            }
        }
    }
    printf("%d %d", x, y);
  return 0;
}

Answer

Visual Representation of Logic

This document provides a visual representation of the logic found in the provided C code.

Overview

The code is a simple program that reads direction commands and modifies x and y coordinates based on these commands. The user inputs a series of commands that indicate directional movement ('N' for North, 'S' for South, 'E' for East, 'W' for West).

Key Components

Variables:
- int x: Horizontal coordinate (East-West).
- int y: Vertical coordinate (North-South).
- int c: Number of commands to process.
- char s[9]: String to store each command.
Functions:
- scanf: Reads the number of commands.
- fgets: Reads each command into the string.
Control Structures:
- for: Loop iterating over the number of commands.
- switch: Decision-making based on the first character of the command string.

Flowchart

Start
  |
  v
Initialize x = 0, y = 0, c
  |
  v
Read c using scanf
  |
  v
For i = 0 to c-1
  |
  v
  Read command s using fgets
  |
  v
   +----------------------------+
   | First character of s       |
   +----------------------------+
   |            |               |
   |            |               |
   v            v               v
 Check s[0]   Check s[0]      Check s[0]
  | 'N'        | 'S'           | 'E'
  |            |               |
  |            |               |
  v            v               v
y = y +       y = y -         x = x +
(int)s[7]    (int)s[7]      (int)s[6]
  |            |               |
  +------------+               |
            |                x = x +
            |                (int)s[6]
            |                  |
            +------------------+
  |
  v
End Loop
  |
  v
Print x, y
  |
  v
End

Detailed Explanation

Initialization:
- Variables are initialized to zero for coordinates x and y.
Input:
- The number of commands (c) is read from user input.
Processing Commands:
- A loop iterates c times. For each iteration:
  - A command string s is read, containing directional information.
  - The first character of s determines the direction:
    - If 'N':
      - Increase y by the value at s[7].
    - If 'S':
      - Decrease y by the value at s[7].
    - If 'E':
      - Increase x by the value at s[6].
    - If 'W':
      - Increase x by the value at s[6].
Output:
- Finally, the updated coordinates x and y are printed.

Annotations

s[7] and s[6] are indexed positions in the command string; interpretation here assumes they hold integer values in character form.
The ASCII values may need to be converted to obtain the expected integer values during the arithmetic operations.

This representation simplifies the understanding of the code's logic by providing a clear depiction of how inputs affect the resulting coordinates through specified commands.

Description

This document visualizes the logic of a C program that updates coordinates based on user input commands for direction (N, S, E, W) and provides detailed explanations of the code's flow and structure.