# Sudoku Programming with C: A Practical Guide by Giulio Zambon

## Sudoku Source Code in C Language

Sudoku is a popular logic-based puzzle game that challenges your brain and reasoning skills. The goal of sudoku is to fill a 9x9 grid with numbers from 1 to 9, such that each row, column and 3x3 subgrid contains every number exactly once. Sudoku puzzles come in different levels of difficulty, from easy to evil, depending on how many numbers are given at the start.

In this article, we will show you how to create your own sudoku game using C language, a powerful and efficient programming language that allows low-level access to memory and hardware. C language is ideal for sudoku programming because it has a simple syntax, a rich set of operators and functions, and a fast execution speed. We will use Code Blocks IDE, a free and open source integrated development environment for C/C++ programming.

## sudoku source code in c download

## Sudoku Game Code in C Language

To create a sudoku game code in C language, we will follow these steps:

### How to create a new project in Code Blocks IDE

Open Code Blocks IDE and click "Create a new project".

Select "Console application" and click "Next".

Choose "C" as the language and click "Next".

Name your project as "Sudoku" and choose a location for it. Click "Next" and then "Finish".

A new project with a main.c file will be created.

### How to fill the board with random numbers

First, we need to declare some variables and constants for our program. We will use a two-dimensional array of integers to store the sudoku board, a constant N to represent the size of the board (9), and some variables for loops and random numbers.

We will also include some header files for standard input/output functions, time functions, and assert functions.

#include <stdio.h> #include <stdlib.h> #include <time.h> #include <assert.h> #define N 9 // size of the board int board[N][N]; // sudoku board int i, j, k; // loop variables int num; // random number int row, col; // board coordinates int count; // number of filled cells srand(time(NULL)); // seed for random number generator

Next, we need to fill the board with random numbers from 1 to 9, such that each number appears only once in each row, column and subgrid. We will use a nested loop to iterate over each cell of the board, and a do-while loop to generate a random number until it is valid for that cell.

We will also use a function called checkvalid() to check if a given number is valid for a given cell. This function will return 1 if the number is already present in the same row, column or subgrid, or 0 otherwise.

// function to check if a number is valid for a cell int checkvalid(int num, int row, int col) { // check row for (j = 0; j

// check column for (i = 0; i

### How to check if the board is valid and solvable

After filling the board with random numbers, we need to check if the board is valid and solvable. A valid board is one that follows the sudoku rules, and a solvable board is one that has a unique solution.

We will use a function called checksolvable() to check if the board is solvable. This function will use a backtracking algorithm to try all possible values for each empty cell, and return 1 if a solution is found, or 0 otherwise.

We will also use a function called removecell() to remove some numbers from the board to create empty cells. This function will take a parameter k, which represents the number of cells to be removed. We will use a random number generator to select the cells to be removed.

// function to check if the board is solvable int checksolvable() int row, col; // find an empty cell for (row = 0; row 0) row = rand() % N; // generate a random row index col = rand() % N; // generate a random column index if (board[row][col] != 0) // if cell is not empty, remove it board[row][col] = 0; k--; // decrement number of cells to be removed

### How to display the board and user input

Next, we need to display the board and user input. We will use a function called displayboard() to print the board on the console. This function will use some formatting characters to create a grid-like appearance.

// function to display the board void displayboard() printf("\n"); for (i = 0; i

### How to solve the board using backtracking algorithm

Finally, we need to solve the board using a backtracking algorithm. This algorithm will try all possible values for each empty cell, and backtrack if a dead end is reached.

We will use a function called solveboard() to implement this algorithm. This function will be similar to the checksolvable() function, except that it will also display the board and the solution steps.

// function to solve the board int solveboard() int row, col; // find an empty cell for (row = 0; row

## Conclusion

random numbers, check if the board is valid and solvable, display the board and user input, and solve the board using a backtracking algorithm. We have also provided the source code and the output of the program.

Sudoku game is a fun and challenging way to exercise your brain and improve your logic skills. You can download the source code from this link and run it on your computer. You can also modify the code to create different levels of difficulty, add graphics and sound effects, or explore other applications of C language.

We hope you enjoyed this article and learned something new. If you have any questions or feedback, please let us know in the comments below. Happy coding!

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